NEPA cuts the light while your PC is running, or the generator fuel runs out unexpectedly. You restore power, you press the power button, and your PC either doesn't turn on at all, starts making strange sounds, or gets stuck before Windows loads. This is one of the most common scenarios we deal with from users across Abuja, Lagos, and elsewhere in Nigeria.
The good news: most post-power-cut boot failures are fixable without replacing hardware. The cause determines the fix, and there are a logical order of steps to work through.
Scenario A: PC Won't Power On At All
If the PC shows no signs of life after power restoration, the most likely causes are:
- The PSU tripped its internal protection. Some PSUs have a self-protection mode that requires a full power cycle. Switch the PSU power button off (the rocker switch at the rear of the PC), wait 30 seconds, and switch it back on. Then try the power button.
- The UPS is not providing output. If you're on a UPS, check that it powered on and is providing output. A UPS with a dead battery may not switch back to mains output cleanly. Test the socket the PC is plugged into with another device.
- The power surge killed the PSU. If the power went out due to a surge event, the PSU may have sacrificed itself. Try the PSU power button reset above; if there's still no response, the PSU has likely failed and needs replacement.
Scenario B: PC Powers On But Screen Is Black or Shows Error
The PC fans spin and lights come on, but you see a black screen, a blinking cursor, or an error message like "No bootable device found" or "Operating System not found."
Step 1: Check BIOS and Boot Order
A power cut can sometimes reset the BIOS to default settings if the CMOS battery is weak. When this happens, the boot order may be reset, and the PC tries to boot from a device that has no operating system (like a USB drive or network boot). Enter BIOS setup (usually by pressing Del, F2, or F10 during the very first screen after power-on — the exact key depends on your motherboard). Find the Boot Order or Boot Priority section and ensure your Windows drive is listed first. Save and exit.
Step 2: Check If the Drive Is Detected
While in BIOS, look for a section showing detected storage devices (usually under Storage, SATA Configuration, or similar). Your hard drive or SSD should appear here by name. If it doesn't appear, the power cut may have damaged the drive connection, or the drive itself may have failed. Check that the drive's SATA or power cables are firmly connected (open the case to verify).
Step 3: Attempt Windows Startup Repair
If the drive is detected but Windows still won't load, the file system or boot sector may have been corrupted by the sudden power loss (especially if Windows was actively writing when power was cut).
- Create a Windows 10/11 bootable USB on another PC using Microsoft's Media Creation Tool
- Boot from the USB (you may need to change boot order in BIOS to prioritise USB)
- When prompted, choose "Repair your computer" rather than "Install now"
- Select Troubleshoot → Advanced Options → Startup Repair
- Let Windows attempt to automatically fix the boot issue
Startup Repair fixes the majority of boot sector and BCD (Boot Configuration Data) corruption that power cuts cause.
Step 4: Run CHKDSK to Repair File System
If Startup Repair doesn't resolve it, go back to Advanced Options and select Command Prompt. Type:
chkdsk C: /f /r
This scans your system drive for file system errors and bad sectors, and repairs what it can. It may take 30–90 minutes. If it reports finding and fixing errors, restart and try booting normally.
Step 5: Consider a Windows Repair Install
If file system repair doesn't work, a Repair Install (sometimes called an in-place upgrade) reinstalls Windows files over the existing installation without deleting your personal files. From the Windows setup USB, choose "Install now" → accept licence → when prompted, choose "Keep personal files and apps." This fixes deeply corrupted Windows files while preserving your data.
When the Drive Itself Has Failed
If the drive isn't detected in BIOS, or if CHKDSK reports uncorrectable errors, the drive may have physically failed from the power event. In this case, file recovery becomes the priority before anything else. Stop trying to boot from the drive and focus on recovery (see our guide on recovering files from a dead PC).
The CMOS Battery Factor
If your BIOS reset to defaults after the power cut, the CMOS battery on your motherboard (a small coin-cell battery) may be too weak to maintain BIOS settings when the PC is off. Replace it — it's a CR2032, costs under ₦1,000, and is easy to swap. After replacing, you'll need to re-enter BIOS and set the correct date/time and boot order.
Preventing This in Future
A UPS with battery backup is the essential preventive measure for Nigeria. A UPS gives you several minutes to save your work and shut down properly when power fails — preventing exactly this kind of file system corruption. It's not optional; it's the cost of running a PC reliably in Nigeria.
Not sure what's wrong after a power cut? Our team can diagnose and fix it →