Not sure if this helps at all but after having some work done on my car which involved having the battery off, my Kufatec lost pretty much all of its connections.
Lost the ability to answer the phone and also the display on the dashboard disappeared.
VW basically disconnected the Kufatec bluetooth kit and started the engine.
Then turned the engine off. Reconnected the kit turned the engine on and everything reappeared.
Worth a try
