Chosen Solution
I took it to the “Genius” bar and was told the problem was caused by my logic board. The genius, picked up my laptop and flexed the bottom. The lines/other disruptions showed up on the screen and the System crashed. I was told since I replaced the optical drive with another hard drive and replaced the battery, I should take it to a specific shop to do the repair. I took it in and the repair assistant told me not get the repair because of the VST defect and the problem can return. Do the iFixit logic boards for 2012 13” MacBook Pro 2.9 GHz have a repaired/non systematic VST? Thanks for any help
Computers are not supposed to work with bottom flexed. Try checking the RAM modules, reseat them in place, sometimes they are not perfectly inserted in the slot and despite they work, as soon as you put pressure on the bottom cover RAM moves a bit and causes a kernel panic as it may be expected. I’m with @danj on this, never heard this “VST” and can’t imagine what the “genius” is talking about.
