LG G5 took a hit, screen isn't cracked but phone won't boot.

My phone took a hit and now it won't boot. The screen isn't cracked and doesn't seem to be broken. When I attempt to power it on it vibrates, the blacklight shows briefly, and the notification light snores blue but that's all I get. No power up sounds or anything. I've opened it up and checked out the insides, checked all connections as best I can and everything seems to be in order, plugged in, nothing out of place or broken, etc. I've attempted to boot into recovery mode and no dice.

It's obviously highly likely that there's a hardware problem. I have little option but to repair this phone but I don't know which part I should be replacing. I can't afford to order parts at random until something works so if someone could give me some direction that'd be great. Thanks!