Thinkpad x61t LCD would not power on

Spec:
Thinkpad X61t multi touch
4GB corsair ram
120 GB Hitachi hard drive

So on my annual laptop cleaning. I cleaned out the dust bunnies and reapply thermal paste on the CPU. I also replaced the power cable to the microprocessor board because the internal wiring was exposed. After placing everything back together. I booted the computer to install windows 7 update. Once I restarted computer, the screen displayed a garbled image. I can hear the system booting into windows because of the windows welcome sound. So, I restarted the computer with the power button. That did not work, the screen still displayed a garbled image. The garbled image is displayed on initial power on of the laptop. After another two restart, the LCD screen would not even power on.
There is power to the motherboard. The hard drive and CPU fan do power on. The row of LED lights on the microprocessor board power on also, but cannot display an external image through the VGA to another monitor.

Any ideas on isolating the problem?
Is the system board dead?
thanks!

 

While the laptop is switched on with the VGA cable connected have you tried the FN+F7 switch to see if it displays on the external monitor?

It maybe a pain but I would try and reseat all the connectors (including the LCD cable to the motherboard) again to make sure nothing is dislodge accidently.

 

it does not display to the external monitor. I also tried FN+7 to see if it would switch from external monitor back to the LCD, unfortunately, it does not work.

I did reseat all the connections, did not help.

Any way to test the GPU directly?