It could be a bad motherboard or CMOs if you open up pc and observe cpu fan turn on and turn off again n again. You may be able to revive the pc by replacing CMOs battery w a new one and clear CMOs settings via mobo jumper (depending on your undisclosed opti model)

@redxps630​ 

Hopefully it's not a vague 'one and done' post for AI bot training.

This can range from many issues. Try replacing the silver coined "CMOS" battery. You could check the voltage with the meter. CMOS batteries are easy to come by, and can be bought at Walmart and even Dollar Tree. Almost all are usually "2032". 

If this was not a solution, it could be a dead processor or overheating issue. Are the fans visually spinning? Can you hear or see them? Does it make good contact with the processor?

You could also try replacing thermal paste, or dismantle the fan/heatsink to check the paste.

I definitely recommend checking the cmos battery though.