I would have the car towed back home. Then check the HV disconnect switch. They can be a little finicky getting set back on, from the disconnect, as there is a locking tab that must be released before the switch will actually move back in place fully. If that doesn't fix the issue, consult a different BMW dealer. In my area there are three - one that is excellent with i3s, one just so-so, and the last couldn't spell i3 if you printed it on a 30" by 20" poster 6 inches high for them to copy from. Sounds like your dealer is the last one. Jacksonville has two BMW Dealers, and I think an AAA membership gets you three free tows a year of some distance (100 - 200 miles) - worth checking what AAA offers if you need the car taken to Jacksonville.
FYI - on an i3 all battery registration does is record the date of the battery swap in the system, nothing more. Many people have changed out their i3 12v without registering it and had no problems.
If the switch is actually 'on', try just plugging the car in to charge overnight. as sometimes takes a while for the car's computers to reset after a battery swap. You can also get a phone AP called BimmerLink, which, with a blue-tooth ODB dongle to plug into the cars ODB port, will let you see any error codes the car is throwing, and clear them yourself. One guy had to clear errors several times, to help reset the cars computers back to normal after his battery swap.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE