Normally I would say that symptom indicates the hard drive has either failed or the bootloader is corrupt. Considering the power outage and the PSU replacement, I would first verify the PSU replacement to be OK. On a working computer, make a bootable disk or USB to check that the PC actually works OK. If you want to kill two birds with one stone, make a Windows 10 install media
If you can boot to that, then
On the initial setup screen, enter your language and other preferences, and then select Next. If you're not seeing the setup screen, your PC might not be set up to boot from a drive. Check your PC manufacturer's website for info on how to change your PC's boot order, and then try again.