I think it is not SW, but HW problem. MK4 turns on, if there is i-bus traffic. If you unlock the car, the red led must light. If it doesn't, it is the failure of the power supply or power part on the mk4 main board. The worst case, when an mk4 does not turn on even when you turn on the key, only when you press the eject button. Tricky sellers are selling these units with short-cutted eject button, then if you connect the mk4, the menu is shown, but the unit never goes to sleep mode, and drain your battery at 1 night. :-(

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Bombolo