I experienced the same behaviour with Groove 52HPn after testing and setting the CPU frequency to 400MHz.
Device started, Link is up, but not reachable by IP.
Here is what I did to solve the problem:
-hold reset button before powering device on startup for 3 seconds and then release (bevore lights start flashing (http://wiki.mikrotik.com/wiki/Manual:Reset_button
-device is now loading in backup bootloader
-wait until it is accessable by winbox
-set the CPU frequency up to at least 500MHz
After the reboot the device will be able to load in normal boot mode and work normally.