1stRS

https://www.reddit.com/r/Audi/comments/l1vi40/bought_rsq8_crashed_the_mmi

check out this link. The owner says his MMI is stuck on the loading screen, and someone identifying as an Audi Tech told him to disconnect the battery and touch the two terminals together...
I’m no tech, but I’ve read here on the forum that the 48v system doesn’t like to have the battery disconnected. Anyone know if this is a way to reset modules on RSQ8?

retom

Disconnecting the battery in a car like the Q8 is very risky and should not be done by an ordinary user. Disconnecting the 12V battery, which is located under the front passenger's feet, will cause errors in most car modules that need to be cleared one by one. Some modules as windows or sunroof will also require additional re-learn. This operation will also delete all car user settings.
Disconnecting the 48V battery, which is in the trunk, is not allowed except for an authorized Audi service center because it requires specialized equipment.
In the event of MMI freezing, a hard reset usually helps, i.e. pressing the radio volume **** for about 20 seconds until both screens go out.