imac turns off by itself once in a while and wont turn on

hello so i have an imac, it’s been in use alright for a few years now. about a month ago it randomly shut down when i was using it (not something strenuous, just on google) and wouldn’t turn on with the power button. i tried unplugging and replugging stuff to no avail and eventually it turned on when i put the plug in the socket next to it.

it just happened again, tried transferring the plug into the other socket like last time and it doesn’t work. plugged my phone into both sockets though, and it charges fine. swapped out the iMac’s original charger for a different one, it doesn’t turn on. moved the pc to a different socket in the house, still doesn’t work.

how do i fix it? could it somehow be because of an older hard drive i downloaded onto it (backup files of my ipad) around a month ago? the computer is fine most of the time though, and i don’t think it was overheating.