I was experiencing these exact issues with my ‘21 Ram 1500
My truck died on me on the way to the dealership & had it towed the rest of the way. The tow guy tried jumping it to at least get it in neutral and on to the truck but wouldn’t hold the charge after removing the cables. Do you think that means I have no charge in my MGU either? What did you end up having to do for your situation? I planned to get my truck towed back to my home from the dealership and work on it with my buddy following @UpNorthEngineer write up.Great info and thanks very much for sharing. After about a month of starting to hear some bearing whine, my MGU is now dead with no charging at all. So I'm probably past just a simple bearing replacement and I've got a dead $60k truck.
FWIW, I came across a reddit post showing the bearings as 6003 and 6305. The 6003 would confirm what @UpNorthEngineer measured. Not sure on that front bearing but I'm passing the info along in case it helps anyone.