EW846 for VW can't start the screen
The key needs to be switched to the ACC setting. Test the red and yellow line voltages with a voltmeter. When the device is turned on, there must be voltage on both yellow and red wire.
If there is voltage in the ACC file, the machine will not boot and the machine is broken.
If there is power in the red and yellow lines of the original car power cord, but not power from the red and yellow lines of the small plug , indicating that the CANBUS box or cable is broken. Need to replace the cable