Continous reboot after replacing USB port and battery

I’ve replaced my battery and USB charging port and it went as well as could be expected. However after reassembling everything, the screen goes white with the “Google” logo for a few seconds (as normal) but then goes black for a few seconds before the whole process repeats.

It is continuously trying to re-boot. Any ideas as to what is wrong?

Edit: If I hold the “volume down” button during the reboot loop, it enters the bootloader(?) (Android robot shows on screen) mode where I can power it down. Anyone have a suggestion as to how to proceed?