Is the red light intermittent?
I just installed a Phatbox (from a BMW) into my Audi RS6. Red light would come on then off, then on then off and so on.
For some unknown reason it need a ground wire to work.
Ran a wire from mounting bolt to chassis and all is good.
If that does not work I got this from Phatnoise.
Thank you for using the PhatNoise Car Audio System! You will need to
downgrade to version 5.02 of the Audi firmware. Please format the PHTSYS
partition ONLY according the instructions in this link:
http://www.phatnoise.com/kb/index.php?page=index_v2&id=77&c=3You may download the firmware at the following link:
http://phatbox.sixpak.org/firmware/?Audi-Native=5.02Download all 4 zip files for Audi.
Right click the files in any order, and select "Extract".
Under "Select a folder to extract the files to," click Browse Expand the
section under "My Computer" Select PHTSYS, then click OK.
Follow the same process for all 4 zip files.
Once the files are extracted to the root directory, you may eject the
DMS from your computer by clicking the green arrow icon in you computer
tray (next to your computer's clock". Click on "Safely Remove USB Mass
Storage Device".
You may now remove the DMS and follow "PART II: In Your Car", of the
instructions in the following link:
http://www.phatnoise.com/faq/firmware_update.phpPlease let us know if we may assist you further.
Best regards,
PhatNoise Customer Support