Could it be possible that you're losing connection and it triggered the failsafe? Try steering right when it brakes or go in a circle to see if it's disconnecting, closed parking garages aren't always the best place for connection. Also, snip off that Tamiya connector and get a Deans soldered on ASAP, those Tamiya connectors love to melt, even on a 6s 7.2v NiCd!