Why does my iPhone keep restarting?

Every time I open my iPhone it will stay on for a short period of time and then restart. Sometimes when it’s on charge it will last longer but most of the time I get less than a minute of use before it restarts. It either restarts to 10% or 1% when turns back on and then after a few more it will go back to what it was at before. It only changes charge by a large amount when it takes a long time to turn on. It doesn’t restart when I’m searching on on a browser, sometimes it restarts when I’m on YouTube and it always restarts quickly if I’m playing a game

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0

crwdns2944067:04crwdne2944067:0:

Hey, I’d start by checking the battery health to see what percentage performance you’re at. Below 80% is definitely a battery change.

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

It’s at 89 and the entire back is shattered. I check the panic logs but couldn’t find anything

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

Gee that’s no good, the only way to quick test is pull motherboard out & test in an un damaged donor phone. Apart from unknown device prompts if it functions then you can start to look at troubleshooting your assembly components.

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

If it does the same on donor phone back assembly then there’s an issue on your mainboard

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

crwdns2934285:0crwdne2934285:0