Did you ever fix this.
The RS6 has two main fuses. One supplies the starting and charging ans the other supplies everything else.
It's highly unlikely that you've blown both of them. I thin the charging/starting one is 200A and the other one is 150A.
You say that you used a DVM and checked your battery, correct?
As ttboost said, above the washer fluid reservoir is where there's a little panel that can be removed. This is where the battery positive is, which then supplies the main fuses. Put the DVM probe on this and touch any ground to see if the battery power is making it up to the front of the car.
It's really strange that you've got nothing, as if there's no battery at all. I'm thinking that maybe your ground strap in the trunk is disconnected or broken? Maybe add a jumper cable from the negative terminal to another good ground?