MacBook Pro 2012 hangs on startup My 2012 MacBook Pro with Sierra recently started hanging at boot. It seems to start normally; the Apple logo and progress bar appear, but it hangs at about 3/4 of the way through.

Right before I first had the issue I was using the machine normally then very suddenly (I'm not sure what triggered it) there were display issues where vertical lines appeared on the screen and the computer became unresponsive. I restarted it and it never came back up.

The same problem occurred when I tried to boot into the recovery partition and Windows 7.  I thought this was a hardware problem so I started the Apple Hardware Test with option-D and ran a diagnostic. It came up empty, no issues.

I remembered that I had an old Time Machine backup sitting around. I tried to boot from that but after a few seconds the screen went blue with small black vertical stripes.

Does anyone know what the issue could be and how or if I can fix it?
Black stripes on blue screen and booting problems is very alike a GPU problem just like MacBooks 2011 had. 
Though, to surely check it is not software you may try backing up data to another computer (requires removing Mac's HD and putting it into external case), format it and install a fresh MacOS from a flash drive.