Firstly Bluetooth and LEGACY are not exclusive to one or the other basically either the legacy radio board dumps serial data into the main motor driver or the Bluetooth receiver does. You can even happen at the same time and contradict each other that’s why where’s a Bluetooth on off switch.
Obviously this is a locomotive issue, if you don’t see where the handrails are obviously grounded then check continuity between a handrail and the outside rail or a driver. Also try holding your hand over the locomotive during power up/ operation
