Weird YLOD on slim PS3 after RSX delid

While using the system today (a 2k series slim) the fan went up higher than usually, a quick check via CFW showed the RSX at 80-81°C (which is a tad too hot according to the interwebs).
After reading up a bit, a lot of places suggest delidding the RSX and CELL to replace the TIM that sony used because it doesnt age well.
After delidding the RSX (using a hairdryer to warm it up since it was suggested to make it easier to get the IHS off) and deciding not to do the CELL (since I dont have the tools to safely get through the glue) and putting everything back together, I powered the system on, only to not get any video via HDMI. After about 20-30 seconds, the system shut off with the LED flashing red.
Took it apart again, checking all connections again (verified that the IHS of the RSX was on correctly, while feeling for any heat (which there was none, the IHSes themselves barely got warm to the touch), put it back together and this time, hooked up the system via both, HDMI and AV port. Powered it on, the TV immediately recognized that something was up on the input for the AV port but lost signal after a second. Then blank screen until the system shut off after just about the same amount of time. This time, I had a close look at the LED and managed to catch a glimpse of white/yellow.
The old posts/guides on YLODs (from the days of phat systems) suggest broken solderjoints due to overheating of the system (which is definitely possible due to hairdryer) but the timings are off: the affected systems YLOD after just a second or two, while mine takes its sweet time before shutting off.

tl;dr: I delidded my RSX and managed to apparently YLOD the system, but time between poweron and YLOD doesnt match up with old posts about it.

Are there any hints on potential fixes/things to check or did I brick the system with the hairdryer?
(would really like this system to survive due to personal reasons)

 

In removing the heatspreader you put physical stress onto the package, that in itself can be enough to mess up either the solder balls or more likely the microbumps connecting silicon and substrate.
Given it's already in a weakened state i can see that being the cause.

My CECH-2000 died with a YLOD too from one day to the next, the yellow is hardly visible before it transitions into blinking red.
Replaced it with a 2100.

 

Alright then, I guess this will be a project later on, if i ever get the equipment to do a reballing.