Blacklight without graphics (MBP Mid-2012)

Long time lurker, first time poster.

Hello everyone. I own a Macbook Pro, mid-2012 (101) model, intel i5. I upgraded the RAM to 16GB and the HDD to 2TB last summer. I noticed a while back that my MBP ran hot and throttled more often than usual. I searched online for solutions and I read about applying new thermal paste. I purchased the ArctiClean kit as well as the Arctic Silver thermal paste from Amazon, and was careful with the cleaning process and application using a guide from iFixit on how to apply the paste. I reassembled the Macbook Pro and the display came on fine, the fan was blaring out of control, and further research indicated that I didn't apply enough thermal paste, so I once again disassembled, added a little more paste based on the suggested amount, and put it back together. This time however, when I cut the computer on, the chime sound happened and everything but the screen was black! I sat there for a moment, and the backlight and keyboard light came on (which meant the computer booted up) but there was no actual picture, just the blacklight. I double and triple checked all connections on the logic board to make sure that everything was fit and secure, but there was no luck. I reset the SMC and PRAM numerous times, no luck. I know my warranty is void so I'm not going to bother taking it to an Apple store, does anyone have any suggestions?

P.S. - There is no drop or water damage to the computer