summitradio

So I left the lights on and killed the battery on my 08 A8. No problem break out the battery charger and recharge it overnight.
Next day and it wont start despite being fully charged. Lights and some other dash work but the car wont even crank. nothing!
Looked over various threads and nothing really addressed this issue directly. Well after a day of research I found a proceedure in the
service manual...

If battery was removed and installed without back-up power supply, perform following procedures after connecting the battery:
♦ Deactivate service mode for telematics control unit in “Guided fault-finding”.
♦ Activate automatic open/close function of electric window regulators - see ⇒ Owner's Manual .
♦ Turn the ignition key in ignition lock once to the left as far as the stop.
♦ Synchronise spare keys and additional keys to ensure correct remote control operation.
♦ Interrogate event memories of all control units and erase “Low voltage” event if displayed ⇒ Vehicle diagnostic tester

DO THIS ONE ♦ Turn the ignition key in ignition lock once to the left as far as the stop.
IT will reset the car and it should greet you with a littany of clicks and dings of a waking Audi.

It worked for me!

George