update: there is no update.
new mobo, new TIM, PC still dead. Lights up, ethernet flashes, no output video. Not from GPU, not from CPU. Did the whole "one ram stick at the time , in one different ram slot at the time" as well.
Obviously no CMOS to reset as no BIOS settings yet.
Monitor works but not getting any video.
New GPU has the "Arc" logo that lights up, fans spin, so PSU is fine.
Not really possible that i damaged the CPU, as i didn't even unmount it from mobo previously, when it had already died. Have used various anti-static tricks to be extra extra careful.
f* it, tomorrow i will be going, for the first time in 30 years, to the computer repair shop.