You're quite lucky in that regard, and you're right about the loan phones, it only takes a few rotten apples to ruin it for everyone, and my phone arrived at the Samsung repair centre this morning, so hopefully shouldn't be long now.
If its battery they will do a 5min swap. I learned this week how to use my 3D printer to repair the back glass on my S20.
Just heated the printer bed to 100C and used that to maintain a nice hot temp while I pulled the cracked back plate off. Underneath, gives easy access to the battery unit which is simply pulled out like the batteries of old.