Update for everyone here: the issue was what I described above, basically the underside of the seat bottoming out on the battery terminal causing damage to the battery internals. Battery was replaced by husqvarna under warranty, and the dealer tech was able to change the way the cables connect to the terminal to get a little more clearance. I’ll try to get some pictures of the rub marks on the underside of the seat and the new way the cables are routed. Unfortunately I don’t have a picture of the way the cables were routed previously, but maybe one of you can get one and add to this thread. Bike has no problems at all anymore, runs great, no issues with engine cutting out even on hard braking .
NOLO, check the underside of your seat for rub marks in the plastic caused by hitting and rubbing on the battery terminal. I’ll try to get some pictures of those same marks on my seat so you know what to look for.