Computer won't boot after a power outage or sudden power loss

Symptoms

• Power outage or surge happened right before the problem started
• PC may not power on, or powers on but won't boot Windows
• Sometimes shows disk check or boot repair screens
• Surge protector or UPS, if any, may have tripped

Likely causes

• CommonFile system corruption from an improper shutdownWindows wasn't able to close files properly, which can damage the file system.
• PossiblePower supply damage from a surgeA significant power surge can damage the PC's power supply, sometimes without visibly destroying it.
• PossibleDrive corruption or damage from sudden power loss mid-writeA write operation interrupted by power loss can corrupt data at that location on the drive.
• PossibleTripped surge protector or UPS not passing power throughSome surge protectors sacrifice themselves during a surge and stop conducting power, mimicking a PC failure.
• Less commonMotherboard or component damage from the surgeSevere surges can damage internal components even without a fire or visible harm.

What to do

1. First confirm the PC is actually receiving power: check that the outlet works with another device, and that any surge protector or UPS in the chain isn't tripped (many have a reset button or indicator light).
2. If the PC gets power but won't boot Windows, interrupt startup 2–3 times to reach the Recovery Environment.
3. Run Startup Repair, then 'chkdsk C: /f /r' from Command Prompt to address likely file system damage from the improper shutdown.
4. If the PC won't power on at all, check power cables and, for desktops, verify the power supply switch (on the back) is set to on.
5. For desktops, listen for any unusual smell or sound when attempting to power on, which would indicate physical damage needing professional inspection rather than further attempts to power on.
6. If everything checks out but there's still no power, the power supply itself may have been damaged by the surge and should be tested or replaced.
7. Consider adding surge protection or a UPS (uninterruptible power supply) going forward to reduce damage risk from future outages.

Tools and parts

When to call a pro

If there's no sign of power at all after checking outlets and surge protectors, or if you notice a burning smell, a technician should inspect the power supply and internal components before further use.

Safety