Someone Somewhere said:
That looks like the main GPU die, not a diode. Those things are pretty fragile. Yes, all the important stuff is on the other side, but I still doubt it's going to boot up happily.
I certainly wouldn't waste any nice paste until you know it works at all.
Ahh yes sorry die, it works great so far, 44 degrees at 100% load (fan is also silent, don't know why its reading at 2400 rpm) https://i.imgur.com/qENtUU2.png
I've never seen damage like that on a die, it looks burnt