Bootloop after battery repair

I changed my iPhone X's battery and tested everything before closing it up. The phone booted and behaved correctly. I left it on its own for a while and came back to a boot loop. I've seen people mention that a connector is probably damaged, but I checked all the ones I unplugged for the repair (battery, touch, display and earpiece) and made sure they are well connected. I don't know what else to try. Any ideas?