Nope, chances for hacking.like that are zero to none. Whats more likely is he has acces to some accout somewhere or some your email that you use.

smart socket is not a good way to turn pc on or off

Macrium reflect. If you gonna use bigger drive then the old one, after you restore the image just use disk management to expand the partition.

this is such a mess, not sure what to tell you. if it were me id strip the pc to bare esentials and try to triubleshoot thing one by one from there.

having a family friend repair guy only makes this easier by being able to borrow stuff like memory or old gpu for troubleshooting.

also clean windows are a must.

troubles started when you upgraded bunch of stuff or after? it can be the mobo, it can affect everything.

what was your old psu?

is your bios updated? how are things setup in bios, cpu, memory, everything?

install new windows on ssd,

set boot drive in bios to ssd,

for simplicity sake, conect you old hdd after you install windows on ssd. i would back everything up and wipe it, then copy stuff back to it. it would clean stuff up for future.