Laptop screen won't turn on and system fails after cleanout

We have a Dell Inspiron 1525. It has been having overheating problems for a while, so tonight I opened it up, removed the heatsink, cleaned out the clogged up fan and cleaned/replaced the thermal paste on the CPU. While taking off the heatsink, the thermal pad that was on the GPU tore. I didn't have another pad handy, so I used (non-conductive) thermal paste on that as well. Also, while I had the heatsink out, I inspected the CPU and found that one of the corner pins was actually bent outward (yes, it came from the factory that way!), so I (very carefully) straightened it before reseating the CPU.

Now, when I try to start the computer the screen stays completely blank (no Dell logo, no command lines, nothing), the HD and disc drives spin, and after a few seconds the entire system dies...

I've researched here and elsewhere for similar problems, and have tried some of the suggested solutions (unplug power, hold pwr button 30 sec, plug in power, and boot; remove/swap the memory) but so far nothing has worked.

What could the problem be? Could switching from a thermal pad to thermal paste on the GPU cause this? Or straightening the bent CPU pin? Could it have been intentionally bent to work properly? I've certainly never heard of such a thing...

Any advice that might help would be greatly appreciated!

Thanks