to update.zip and place it inside the udisk folder.
2.3 Backup and data migration Mounting internal partitions read-write (or using recovery/ADB) allows creating full backups (nandroid) or extracting user data for migration, diagnosis, or archival.
Once you have the correct update.zip file, follow this exact procedure. Your car stereo does not automatically recognize the command; you must trigger the recovery mode manually.
The text mnt/media_rw/udisk/update.zip is a specific file path used by (and similar T3-based) Android car head units to locate firmware updates on an external USB drive. If the system is prompting for this path, it is looking for a local update file to begin a system flash or software upgrade. Understanding the File Path