I've already tried to get the dock battery drained, then fully charged, reset the tablet several and also did a factory reset today. Nothing seems to help. As a last resort I opened up the dock hoping to find some sort of connector not plugged correctly or some other visual indication of something broken but everything seems fine.
I'm running a stock 4.2.1 ROM and the MobileDock version is DOCK-EC20N-0207.
In the attached image you'll see the result of the alphabet and the numbers 1 to 0.
I've searched all over xda and Google but no solution or similar problem. Help?