Sometimes the solution would be easy….

…damn I swapped Rx and Tx and everything went fine,
and I was so sure I connected, documented and even checked multiple times that all is as it should.

At first I thought the level shifter isn’t working, but my brand new Open Workbench Logic Sniffer showed signals, same signals before and after shifting, and was even able to autobaudrate guess my GPS defaults which is 38400.

As I 3D printed a case for the cubieboard I needed to remove the board from the robot anyway so I had the chance to look at the tiny pin headers again, oh and yes I swapped the cables for Rx and Tx there…. damn.