Video issue after T420s disassembly

[ihavebrokenstuff]

Hello Everyone,

I acquired a t420s in decent shape a few months ago and have been working on getting it working well as a spare/leave in the car laptop. I opened it up yesterday to repasted the cooler and replace the fan and now it won't post. I get a white screen followed by a black screen and one beep followed by two beeps.

From what I can find this indicates a GPU or mobo error. Any idea what I did to cause this and if it can be fixed?

Thanks in advance for any ideas.

[Cigarguy]

When you disassemble there are lots of opportunities to mess things up in the reassembly. Was everything working properly before? If so then that is a good known.

Beyond that check the obvious, is the CPU seated and tightened down properly. A few times I did not turn the screw to tighten the CPU which never seated and the machine would not post. Is everything back in place the way it should. Check for a shorts and that all connections are made. Check for shorts.

Take your time and methodically double and triple check everything.