> ## Documentation Index
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> Use this file to discover all available pages before exploring further.

# Troubleshooting Windows Boot Issues (Complete Guide)

> Diagnose and fix Windows PCs that won't power on or get stuck at the boot screen, from checking cables to repairing the MBR and beyond.

Windows boot failures fall into two distinct categories: the machine shows no signs of life whatsoever, or it powers on but stalls somewhere before reaching the desktop. Identifying which category you're dealing with is the first step, because the root causes and fixes are fundamentally different. Work through the sections below in order, stopping as soon as the system boots successfully.

## Step 1 — Determine the Failure Type

Before touching any settings or tools, observe exactly what happens when you press the power button.

<Steps>
  <Step title="Check for any power activity">
    Press the power button and watch for fan spin, LED indicators, or any display output. If absolutely nothing happens, proceed to **Power Connection Checks**. If the machine starts but stalls on a logo, loading screen, or spinning dots, jump to **Startup Repair**.
  </Step>

  <Step title="Listen for POST beep codes">
    If the machine attempts to POST but emits a series of beeps before shutting down or freezing, note the beep pattern. Consult your motherboard or laptop manufacturer's documentation — beep codes directly identify failed hardware such as RAM or GPU.
  </Step>

  <Step title="Note any on-screen error text">
    Messages like `BOOTMGR is missing`, `Operating System not found`, or `Reboot and Select proper Boot device` tell you the firmware found no bootable volume, which points to a different fix path than a splash-screen stall.
  </Step>
</Steps>

***

## Step 2 — Power Connection Checks

If the machine shows no signs of life, a loose cable or failed power supply is the most common culprit. Work through each check below before assuming motherboard or hardware failure.

<Note>
  Perform these checks with the machine fully powered off and, for desktops, the power cord disconnected before opening the case.
</Note>

<Steps>
  <Step title="Verify the wall outlet and power strip">
    Plug a known-good device (phone charger, lamp) into the same outlet to confirm it is live. If using a power strip, bypass it and plug directly into the wall.
  </Step>

  <Step title="Inspect the power cable and adapter (laptops)">
    Check the AC adapter brick and cable for fraying, kinks, or burn marks. Try a compatible replacement adapter if available. Confirm the charging LED on the laptop lights up.
  </Step>

  <Step title="Reseat internal power connectors (desktops)">
    Open the case and firmly re-press the 24-pin ATX motherboard connector and the 4/8-pin CPU power connector. Check that all SATA power cables to drives are fully seated.
  </Step>

  <Step title="Perform a hard reset / drain residual charge">
    For laptops with removable batteries: disconnect the AC adapter, remove the battery, then hold the power button for 30 seconds. Re-insert the battery and retry. For laptops with sealed batteries, hold the power button for 30 seconds while unplugged, then reconnect AC and try again.
  </Step>

  <Step title="Test the power supply unit (desktops)">
    Use a PSU tester or the paperclip test (short the green wire to any black wire on the 24-pin connector) to confirm the PSU outputs voltage. A PSU that passes the paperclip test but fails under load must be replaced.
  </Step>
</Steps>

***

## Step 3 — Boot Into Safe Mode

If the system reaches the Windows logo but fails before the login screen, Safe Mode loads only the minimum drivers needed to start Windows, helping you isolate whether a third-party driver or service is to blame.

<Steps>
  <Step title="Access the Windows Recovery Environment (WinRE)">
    Force the machine to enter WinRE by interrupting the boot process three times in a row: power on, and as soon as the Windows logo appears, hold the power button until the machine shuts off. On the third interrupted boot, Windows automatically launches the **Automatic Repair** screen.
  </Step>

  <Step title="Navigate to Safe Mode">
    From Automatic Repair, select **Advanced options → Troubleshoot → Advanced options → Startup Settings → Restart**. After the restart, press **4** for Safe Mode or **5** for Safe Mode with Networking.
  </Step>

  <Step title="Evaluate the system in Safe Mode">
    If Windows loads successfully in Safe Mode, the problem is almost certainly a third-party driver, startup application, or service. Proceed to **Roll Back a Recent Driver** or use `msconfig` to disable non-Microsoft startup services one group at a time.

    ```powershell theme={null}
    # Open System Configuration to manage startup services
    msconfig
    ```
  </Step>
</Steps>

<Tip>
  If the machine won't reach the Windows logo at all, boot from a Windows installation USB (created with the Media Creation Tool) and choose **Repair your computer** to access WinRE from external media.
</Tip>

***

## Step 4 — Run Startup Repair

Windows' built-in Startup Repair automatically scans for and fixes common boot configuration problems.

<Steps>
  <Step title="Enter Startup Repair">
    From WinRE, go to **Advanced options → Troubleshoot → Advanced options → Startup Repair**. Select the target operating system when prompted.
  </Step>

  <Step title="Allow the repair to complete">
    The tool may run for several minutes. Do not power off the machine. After it finishes, it reports whether it found and fixed issues. Restart and test.
  </Step>

  <Step title="Review the Startup Repair log if it fails">
    If Startup Repair reports it cannot fix the problem, the log is written here:

    ```text theme={null}
    C:\Windows\System32\LogFiles\Srt\SrtTrail.txt
    ```

    Open this file from the WinRE command prompt to identify what specifically failed:

    ```cmd theme={null}
    notepad C:\Windows\System32\LogFiles\Srt\SrtTrail.txt
    ```
  </Step>
</Steps>

***

## Step 5 — Repair the Boot Sector with bootrec

When the MBR, boot sector, or Boot Configuration Data (BCD) is corrupt — common after a failed update, improper shutdown, or disk error — `bootrec` can rebuild them without reinstalling Windows.

<Warning>
  Run these commands from the WinRE Command Prompt, not from within a running Windows session. Incorrect use on a multi-boot system can make other operating systems temporarily unbootable.
</Warning>

<Steps>
  <Step title="Open a Command Prompt in WinRE">
    From WinRE: **Advanced options → Troubleshoot → Advanced options → Command Prompt**.
  </Step>

  <Step title="Fix the Master Boot Record">
    ```cmd theme={null}
    bootrec /fixmbr
    ```

    This writes a new MBR to the system partition without overwriting the existing partition table.
  </Step>

  <Step title="Fix the boot sector">
    ```cmd theme={null}
    bootrec /fixboot
    ```

    This writes a new boot sector compatible with Windows to the system partition.

    <Note>
      If you receive `Access is denied` on `bootrec /fixboot`, run `bootsect /nt60 SYS` first, then retry.
    </Note>
  </Step>

  <Step title="Rebuild the BCD store">
    ```cmd theme={null}
    bootrec /scanos
    bootrec /rebuildbcd
    ```

    `/scanos` lists all Windows installations found on the disk. `/rebuildbcd` then prompts you to add them to the BCD. Type **A** to add all found installations.
  </Step>

  <Step title="Restart and test">
    Close the command prompt, click **Continue**, and allow the system to boot normally.
  </Step>
</Steps>

***

## Step 6 — Check the Windows Event Log

If the machine boots but crashes shortly afterward, the Event Log often records the cause before the crash occurs.

<Steps>
  <Step title="Open Event Viewer">
    ```powershell theme={null}
    eventvwr.msc
    ```
  </Step>

  <Step title="Review critical and error entries">
    Navigate to **Windows Logs → System** and filter for **Critical** and **Error** level events around the time of the boot failure. Look for disk errors (source: `disk`), driver faults (source: `Service Control Manager`), or file system errors (source: `Ntfs`).
  </Step>

  <Step title="Export findings">
    Right-click the **System** log and choose **Save All Events As** to preserve a copy before continuing troubleshooting.
  </Step>
</Steps>

***

## Step 7 — Perform a System Restore

If boot problems started after a recent software installation, Windows update, or driver change, System Restore can revert the system to a previous known-good state without affecting personal files.

<Steps>
  <Step title="Launch System Restore from WinRE">
    From WinRE: **Advanced options → Troubleshoot → Advanced options → System Restore**.
  </Step>

  <Step title="Choose a restore point">
    Select the most recent restore point dated **before** the problems began. Click **Scan for affected programs** to preview which applications and drivers will be removed.
  </Step>

  <Step title="Complete the restore">
    Confirm and allow the process to finish. The machine will restart automatically. System Restore is non-destructive to user data but will uninstall any software installed after the restore point date.
  </Step>
</Steps>

<Warning>
  System Restore must have been enabled prior to the failure for restore points to exist. If no restore points are listed, this step is not available.
</Warning>

***

## Common Scenarios & Quick Reference

The accordions below cover the most frequently reported boot error messages and their targeted fixes. Open the one that matches your exact symptoms.

<Accordion title="'BOOTMGR is missing' error">
  This message means the firmware located the boot drive but could not find the Windows Boot Manager. Boot from a Windows USB and run:

  ```cmd theme={null}
  bootrec /fixmbr
  bootrec /fixboot
  bootrec /rebuildbcd
  ```

  If the drive is not detected, check SATA/NVMe seating and BIOS drive detection.
</Accordion>

<Accordion title="Stuck on motherboard logo / BIOS splash screen">
  The system is failing POST or cannot hand off to the bootloader. Enter BIOS/UEFI setup (typically **Del**, **F2**, or **F10** on boot) and confirm the correct boot drive appears in the boot priority list. Re-enable AHCI mode if it was accidentally set to IDE or RAID.
</Accordion>

<Accordion title="Infinite restart loop after Windows Update">
  Boot into WinRE and run System Restore to the pre-update restore point. If no restore points exist, allow the system to boot into Windows normally, then run the following commands from an elevated Command Prompt to repair the component store and system files:

  ```cmd theme={null}
  DISM /Online /Cleanup-Image /RestoreHealth
  sfc /scannow
  ```
</Accordion>

<Accordion title="'Inaccessible Boot Device' Blue Screen on startup">
  This BSOD at boot typically indicates a driver, storage controller, or file system problem. Boot into Safe Mode (Step 3) and uninstall any recently added storage or chipset drivers. Also run `chkdsk` from the WinRE command prompt:

  ```cmd theme={null}
  chkdsk C: /f /r
  ```
</Accordion>

***

## Escalation Criteria

Escalate to Tier 2 or a hardware specialist if any of the following apply:

* All `bootrec` commands succeed but the machine still fails to boot after multiple attempts.
* `chkdsk` reports unrecoverable bad sectors on the system drive — the drive likely needs replacement.
* POST beep codes indicate failed RAM or GPU and reseating/swapping sticks does not resolve the issue.
* The motherboard displays a BIOS error code (Q-Code / POST code) that the manufacturer maps to a fatal hardware fault.
* No restore points exist, Startup Repair fails, and the user's data has not been backed up — data recovery should precede any reimaging.

<Tip>
  Before escalating, document the exact error messages, the steps already attempted, and any Event Log entries. This significantly reduces Tier 2 diagnostic time.
</Tip>