Stuck in bootloop (only outside of restore mode)

So I recently tried to fix my girlfriend's phone, which had a WiFi issue. I accidentally poked a hole in the battery and so had to get a new one. The battery was fine but the wifi still wasn't working (the latch to the motherboard was busted ), so I tried to tape down the latch and it worked for a bit and then when I sent it to my gf in Canada they must've opened it in customs cause the wifi stopped working and then the phone started to do a boot loop so I think maybe they dropped it.

Anyway, I went to a Chinese tech shop and they fixed it for $150CAD -___- anyway. They also couldn't fix the bootloop (they tried to replace the battery) and I have tried to put it in recovery mode and DFU mode to restore, and manually update to latest firmware but it gets about 3/4 to updating the firmware before it loops again. (this is not the case anymore from what i can tell, looks like it didnt reboot at all during recent recovery modes) Anyone know of anything I can try? (SORRY FOR SUCH A HUGE TEXT ON MOBILE!)