Well, I did upgrade to the latest version 6.49.10
and with the rest of the story … I seems like something went wrong with the upgrade of that device.
Only option I see is doing a Netinstall then, as you do not get in that device at all (anymore)
Some of the newer RouterOS versions are just too big for the hAP Lite memory. RouterOS 6.47.9 seems to be the highest version possible for this device.
http://forum.mikrotik.com/t/hap-lite-not-enough-disk-space/127256/1