Ryan check here
https://www.technipages.com/android-stuck-reboot-loop
https://smallbusiness.chron.com/fix-boot-loop-android-78426.html
https://news.ycombinator.com/item?id=30423815&p=3#30425869
"5. Android boot loop water damage
The phone is physically broken by water, external force, or even a short circuit.
That’s why your Motorola phone stuck on startup screen, LG phone, or other Android tablet stuck in reboot loop. Now, keep reading and get the most suitable ways for you to fix bootloop with a full factory reset, or without data loss."
Did they phone suffer water damage by any chance?