RS6 with a persistent 2.9A drain, measured with an ammeter on the battery.
Spec is it should be less than 0.5A

When locking car it's still there, it will run flat overnight unless kept on charger

Pulled all the fuses in the side panel - no difference
Pulled all the relays under the drivers kick panel - no difference
Pulled the ECU (as much as can with half the connector effectively welded on) - no difference

Gave it to experienced Audi Dealer with veteran tech - no clue.

Anything am missing ?