Freezing when back panel is put back on.

I recently noticed that my power button wasn't working correctly. That quickly to it no clicking and not working at all. I haven't purchased the part yet because I'm concerned that there be some other major issue.

The phone will occasionally not turn on or I will see it freeze and the screen will go dim and red and slowly face away in strange way. A bit like when there is a faulting cable on a laptop display. Sometime I can boot it back up by applying power via USB (this is often necessary with no power button ), once or twice it has come back on its own but most of the time I have to open it up and disconnect the battery. I've done this enough time in the car or other low light places that I have to be very careful to not completely strip the screws on the battery connector.

I thought for sure that it was the grounding clip on the antenna but I've cleaned it and fiddled with it to no end. On several occasions I though I found the cause. Loosening and tightening random screw. Twisting the phone slightly....

But my most successful replication has been during the tightening of the bottom pentalobe screws the pull the back panel tight. Specifically the one in the bottom left next to the mic. I'm not sure what this means. Maybe the latch on the top is pulling a component down and grounding/shorting it to something?

Any Ideas?