Try these steps in order, since updates and the Surface Diagnostic Toolkit were already tried:
- Disconnect everything external from the Surface 3. Remove USB devices, SD cards, external displays, Type Cover, and docking accessories. Then test again. Accessories can prevent normal startup or contribute to instability.
- Make sure the device is fully charged with the correct Surface power supply. Plug it in for at least 15 minutes, then try again. If the charger LED is blinking, flashing, or off, that points to a power-supply issue rather than Windows.
- Use the keyboard wake shortcut when it appears frozen or unresponsive. Press Windows logo key + Ctrl + Shift + B.
- Force a restart using the method for earlier Surface models. Because Surface 3 is an earlier model, press and hold volume-up + power at the same time until the screen turns off (about 15 seconds), then release both. Wait 10 seconds, then press and release the power button to turn it back on.
- If the device starts after the restart, check for updates again in the Surface app. In the Surface app, expand Help & support and select Check for updates to open Windows Update. This is still worth doing after an unexpected restart issue.
- If the problem continues, run the Surface Diagnostic Toolkit again or the Surface Repair Tool. Open Start, search for Surface Diagnostic Toolkit or Surface Repair Tool, then follow the on-screen steps.
- If the restarts continue after that, move to recovery or hardware service.
- Start the Surface using a USB recovery drive: insert the recovery USB, then press and hold volume-down while pressing and releasing power. Release volume-down when the Surface logo appears.
- If recovery does not resolve it, use one of the available service options: self-repair, send to Microsoft, or in-person support.
Note: registry cleanups can introduce additional instability, so avoid further registry changes while troubleshooting.
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