The USB mass storage mode leads to a reboot after about 20 seconds. Another phone (which also includes u-boot as a difference) I tried does not suffer from this issue. They both have KP50 and bootmenu 1.11 installed.

Any idea what could be the cause of this reboot? I could install backupmenu as an alternative for the USB mass storage, but I prefer to use the Recovery Console.

Edit: no short term responses, so I used backupmenu instead in a succesfull way to achive my goal.