Old (Late 2013) iMac 27 fried? Any Ideas?

As I run out of ideas I thought I ask around here ...

My iMac 27 Late 2013 doesn't start up anymore. Nor in safe-mode, I cannot enter both recovery or internet-recovery. It well starts at the beginning, but the progressbar gets stuck at a bit more than half way through. Sometimes the screen goes blank and the forbidden sign. I got a few kernel-panics during startup, also.

It's very possible it's a real hardware issue. I got an kernel panic once yesterday and the whole issue today started immediately after a kernel panic today. That were the first kernel-panics I had in years! No good sign.

It doesn't seem to be a volume issue, cannot start from external backup either.

I tried removing and cycle RAM-Modules, no success either.

I though of connect the Imac to my laptop in Target-mode (which i can access) but lack a connection to the usb-c only laptop (/"$%/%"=($%!((§=%/!%§)

I'm about to create a bootable install media, but as nothing boots I doubt this will be any different.

As said, I run out of ideas, obviously I cannot run any diagnostics at that stage. Any hints are highly appreciated, although I get used to the thought this one is bricked.

THANKS!!

(THIS IS PURE SPECULATION and I don't want to start any rumors, but the first kernal-panic mentioned above was when I pushed the system quite a bit trying out the new Adobe Super-Resolution feature which runs on the GPU mainly. Possible it got to hot? Maybe cooling isn't as good anymore after 8 Years and potentially dust inside the iMac (I have never opened it). But probably this is just coincidence.)