The sdcard install of Android 5.1.1 (image number 99) works almost perfectly for us. However, there is one big issue with the EDID communication with the display. It problem is not deterministic. Sometimes, it works for a week, sometimes you get it after every reboot:
When the error happens, there is a recurrent short flash of random noise on the screen. Reconnecting the HDMI cable does not work. A reboot often helps, but not always.
Predominantly, the issue appears right after rebooting, but we have observed it also intermittently in operation.
The Android 6 image didn't have the above mentioned problem, but one has to turn on the display before the DB410c, which is as bad as random noise. Also, the wifi takes minutes to turn on.
That's why we would like to try a newer Android version. In the best of all worlds, newer versions should have less bugs, not more of them.