Came home from a trip to find my 2017 XC90 T6 Inscription had a dead battery in the airport parking lot. Got a jumpstart, drove it home. Went to the auto parts store, bought a new battery, came home and installed it. Car completely dead - even screens wouldn't come on. Called my repair shop, they said to have it towed in. Called a tow truck, he hooked up a battery pack to it, still nothing. Thought maybe I blew a fuse or something during the battery installation, but not sure.

Repair shop tells me the alternator is only putting out 12.3V, needs to be replaced at a cost of $1300. No fuses blown. OK, maybe so, but the brand new battery I bought just happened to be completely dead? What are the odds of that? Does something not sound right here?