Replaced Processor and now system does not POST.

So I really butchered this ‘upgrade’ but wondered if there was anything I was missing.

System is A1419 Late 2015 iMac 27”, with Core i5, R9 M380 graphics.

Firstly, I managed to crack the screen in the first ten seconds of the process :(

Secondly, I then managed to pull all apart ok, although when seating the new processor it shifted and got trapped and very slightly bent the corners of the processor. So the ‘new’ processor likely toast and possibly damaged logic board too.

I pulled the processor out replaced with the original unit and tried to startup and now I have no post. The CPU socket though looks fine and not visibly damaged in any way - why on earth does the spring attachment have to be so tight….

I managed to get some thermal paste on the graphics card surrounding caps(?) - would the thermla paste here be electrically conductive? Would a good paste clean here help? I’ve tried with isopropyl alchohol with no luck.

Replaced clock battery. No change.

So my guess is I messed up the logic board - (I did say it was a butchered process) - but was wondering if the cracked glass would contribute to this issue? My sense is the system would post but not display anything if it was the screen to blame.

Also how likely would it be that the ‘new’ processor is still ok?

I released the ram on the board and reseated it but wondered if the compression maybe needs to be a bit harder to seat it again?

I have a new LB on the way but just in case have I missed anything obvious?

I get two led on startup fan spins gently, black screen … thats it. I’ve tried all the power button routines to try and get some response, but nothing.

Thanks…