It used to be so in older versions of ubiboot so that if the device was powered off and inserted to a wall charger, it went to repair mode instead of charging mode. This was corrected in version 0.3.0 however, so if you have this problem you either have too old ubiboot or the configuration is wrong. (There is a configurable parameter to enable/disable this feature...) Well, you can also just load up ubiboot without flashing it, by pushing it to device with flasher. When it boots up you get the filesystem exports and capability to telnet to the device.