Hi, I’m struggling to remember, but I’m pretty sure it was a poor connection between the two boards. I think there’s a white connector for power and data. that wasn’t making a good connection. Removed, cleaned the contacts, refitted and it’s been fine since. I think there was an option for “programmed” as well if you ordered boards direct from Bosch. Sorry I can’t give more detail, but I’m pretty sure it was just poor connections. Good luck