[PROBLEM] How to restore IMG backup file

[Carpenter]

Software
XBian version: Beta 2
XBMC version: Latest
Overclock settings: Turbo

Hardware
Power supply rating: 1mA
RPi model (model A/B 256mb/512mb): 512mb
SD card size and make/type: 4gb ICIDU
Network (wireless or LAN): LAN
Connected devices (TV, USB, network storage, etc.): TV, USB

Logile
Link to logfile(s):

Problem description:
After updating XBian, it somehow got stuck at the boot screen for no apparent reason after rebooting. Having made a complete backup (in the XBian Config screen in XBMC) I thought it would be really easy to put that back to the SD Card, but when I copied it back with the help of Win32DiskImager it only showed a blinking dash on the screen when starting up.

Did I do something wrong? And is there a way to open the IMG file myself and copy all necessary file to a freshly installed XBian?

How to reproduce: