I just don't think running Mint from a USB could itself cause this. Over the years of building my own computers I have run across a couple times where it would not even power up even though it was shut down correctly just some hours ago. The first thing I would do is disconnect and reconnect every connector and card in my system- it's a desktop and easy to get at. That usually fixed it. If you can't even see your BIOS come up then you aren't getting that initial video signal to your monitor. I'm no expert, but I would start there. Good luck.
i5 3570k, ASRock z77 Extreme 4, 8 Gb Ripjaws 1600, Antec 430w psu, HVR 1600 tv tuner, custom case- marble top, oak face. Carver & DCM Time Window sound system. Mint 14 KDE.