My FP4 has been switching off and restarting during use. I’ve tried disabling 5G as the advice on this sub says the problem is caused by switching between 4G and 5G bands, however this has not solved the problem. Rather the restarts seem to happen when physically moving the phone, most commonly when putting it down on a table, putting it in or taking it out of my pocket, and occasionally when just rotating it between portrait and landscape in my hands. This leads me to think there might be a problem with electrical contact between the phone’s modules - does anyone have insight as to which module I should replace?
Could be the battery contacts.
What I’d do if I where you is to disconnect and reconnect all cables in the phone to rule out the simple things first.
If that doesn’t help, remove the battery and use a wooden toothpick to extremely carefully pull the contacts that connect to the battery maybe 1mm closer in the direction of the battery, so that there is slightly more pressure on the contacts when they touch the battery.
Also make sure none of the battery contacts (both phone-side and battery-side) don’t have corrosion and the backside cover is clipped on properly.