The backup stick makes a complete backup of your head unit onto a USB stick — before you try ADC or anything else. With that backup we can build a firmware stick for exactly your original version if something goes wrong later. That matters most if your head unit does not have firmware 0051: for 0051 there's already the stock firmware 0051, for every other version we have nothing yet.

Status: NOT tested yet! The stick is built, but it hasn't run on a single head unit yet. We'll try it on our test head unit first — until then there's no download. See also the disclaimer.

• It installs two small apps: the Connect app and ADC Backup. Nothing else in the system is changed — that's why it runs on every firmware version, not just 0051.
• Then it copies all 11 partitions of the head unit (boot, recovery, system, vendor, logo and so on, about 1.8 GB together) onto the stick, with checksums and a list of what's inside. The head unit is only read; the only thing written to is the stick. Which partitions those are is under Filesystem & partitions.
• Plug the stick in again afterwards and the Connect app also backs up the T-Box onto the stick, once.

• An empty USB stick formatted FAT32 with at least 4 GB free. The head unit can't read exFAT sticks.
• On a car without ADC this only works via a factory reset: paired phones, Wi-Fi networks and settings are deleted. The firmware itself — exactly what we need for your firmware stick — stays on the unit and ends up on the stick.

1. Switch the car on and plug the stick into the USB port in the centre console.
2. Open Settings › About › Factory Reset and confirm.
3. The head unit restarts, installs the two apps and writes the backup onto the stick. That takes longer than a normal installation — 1.8 GB have to be copied first.
4. When it's finished, pull out the stick — the head unit then restarts.
5. Plug the stick in again: now the Connect app backs up the T-Box. If that doesn't happen, open the ADC Backup app and start the T-Box backup there by hand.

Afterwards everything is on the stick in the folder adc-backup: the backup of the head unit and the one of the T-Box. Keep the stick somewhere safe. We need the head unit backup to build you a firmware stick. The T-Box backup contains your car's data (e.g. the VIN) — better not hand that one on.

Sounds complicated? It is, a bit. But it beats a few weeks without a head unit.