T520 isn't booting up after disassembly

[Dave528]

Basically I wanted to apply some new thermal paste, when I was unscrewing the heatsink I broke one of the screws near the CPU so I gave up.

I also removed the Wi-Fi, Bluetooth and WWAN card since I was planning to sell everything as parts.

I tried to turn on the laptop to test something but it didnt work, there was a black screen, the fan wasn't spinning and no beep.

Only the DVD drive and HDD seemed to work, the power button and battery light was blinking every second.

Here's everything I tried to do:
-Reseating the RAM
-Disconnecting everything except the power and screen cable
-Resetting the BIOS by disconnecting CMOS and holding the power button for 20 seconds, now instead of the light blinking every second it was continously on and was turning off every second very quickly.

I also left the CMOS unplugged overnight, nothing changed. Does anyone how to fix this?

[wyjang]

I know this might seem basic, but just to be sure, have you checked if the power switch jack is seated properly? I've sometimes been surprised after reapplying thermal paste, only to find that I hadn't connected the power switch cable to the motherboard.