Thanks for the feedback.
I gave it a try today and here is the pinout of this board:
Using an FT232R TTL-USB converter the board was nicely talking at 115200 8,N,1. You can find a bootlog attached, if it is of any interest.
I managed to get into the bootloader (gives you only one second to interrupt booting), next thing for me is to learn how to get the content of the mtdblocks off the device (the usb port seems to be active). - I've done some flashing on NAS boxes, but they all can communicate through eth0, so this is a bit different, I'm thankful for any hint or link.
I'd happily contribute to the wiki, but what actually is this board?
It seems quite similar to an EB-600, featuring the same CPU and Display controller, but the memory is 2 pcs.
ESMT M12L128168A, there also is some
29LV160CBTC-70G flash. No clue, if this makes any difference, or if it's just a variant of EB-600.