Just as an update - changed the main loom and after that didn't change anything, changed the di2 SD50 cable from motor to display all all working perfectly.
Trying to work out why my Decoy isn't starting up - Press the on button, Steps logo appears then goes black. Have checked/cleaned all connections and now a bit stuck on what to do next.
Not sure if it's battery dead (3 years old). Motor (replaced recently - only has a few hundred miles). YT bike...