If your Audi MMI (Multi Media Interface) system won't turn on, it is often due to a simple software glitch, a blown fuse, or a break in the fiber-optic communication loop. 1. Perform a Hard Reset
Simultaneously push the Navigation button up, the Radio button up, and press the Center Control Knob down. Hold for a few seconds until the system reboots.
Press and hold Setup (or Menu), the Center Knob , and the Upper Right soft key simultaneously. 2. Check Key Fuses
Press and hold the Volume/Power knob on the center console for about 15 seconds until the screen goes black and the Audi logo reappears.
A blown fuse is a common cause for a completely dead MMI unit. Most Audi MMI systems are powered by multiple fuses located in the passenger-side dashboard or the rear trunk panel. Part 2: MMI Won't Turn On - Amplifier and & Testing