my O2 XDA mini is not switching on........niether by pluging the charger.......when i press the power button with main battery installed....only a red indicator blinks for 4-5 seconds......and when i plug in the charger without main battery installed.....the red indicator continues to glow......its an ununderstandable problem......is this a issue related to backup battery? plz help.........if possible plz tell me the functions of backup battery and which battery can be installed on the place of it.......