Audi A6 Electrical Handbrake and Rear Brake Service Issues

Start by checking the fuses related to the electronic parking brake system, as a blown fuse could cause these issues. If the fuses are intact, inspect the wiring and connectors for any signs of damage or corrosion. Let me know how it goes or if you have any further questions!

The rear brake won't return to the service setting. The fuses are OK.

Since the fuses are fine, try resetting the electronic parking brake system by disconnecting the battery for a few minutes and then reconnecting it. This can sometimes resolve electronic glitches. If the issue persists, it might be necessary to use a diagnostic tool to check for any error codes related to the parking brake system. Let me know if this helps or if you need further assistance!

Unplugging the battery didn't work. The brakes retract briefly and then immediately return to the starting point.

This could indicate a problem with the electronic parking brake motor or the control module. I recommend checking the condition of the parking brake motor and ensuring it is not seized or faulty. If you have access to a diagnostic tool, scan for any specific error codes that might point to the exact issue. If you're unsure or the problem persists, it's best to have a professional mechanic inspect it, as this is a safety-critical component. Let me know how it goes or if you have more questions!