iPhone restarts when on locked screen.

Good day!

My wife’s iOS 10.3.3 16gb White iPhone 6 started doing random restarts like every 2-5 minutes when the phone is locked. It never restarts when it’s not locked. I did some testing, first i connected new battery it did not help, then i’ve installed whole screen from another working iPhone 6, still does random reboots. I even checked leaving any specific application in background before doing lock, does not seem to be related to any of apps.

We also did “full erase”, which did not help.

I’ve checked analytics there are some “panic-full” messages referencing to some “SEP ROM boot” and “timeout waiting for SEP reply to SLEEP control message”. Could not find any information regarding it on the web.

Hoping for your help :)

Here are the analytics:

EDIT: I found that phone may have been damaged by a child in the left bottom corner.

Found out that slightly unbending it from down under caused restarts appear less frequently. But what hardware malfunction may this be?

Photo:

So after many different attempts finally i’ve decided to do hard reset & update it to iOS 12.

Nothing has changed, still reboots when locked.