Screen shows up but touch doesn't work

[gu4cs]

So I dropped my LG G2 and broke the screen. Took it to a repair shop and they replaced the screen but the power flex cable was damaged as well. Got both replaced and now the screen will turn on but the touch doesn't work at all. Also, it occasionally just shuts off and restarts randomly. Can't unlock the phone or anything either... any ideas on how to get this fixed or what's wrong with it? Thanks