XBEE Series 2 working as Router/end device but not as coordinator

Hello, I am new to xbee technology and have just been given 6 xbee Series 2 controllers to setup for a friend.
I am using x-ctu latest version on Windows 7.
I am programming the chips using a sparkfun explorer connected to the pc and have a remote unit with an arduinoXbee shield.
I am using XB24-B ZNET 2.5 ROUTER/END DEVICE AT 1247 and XB24-B ZNET 2.5 COORDINATOR AT 1047 .

From the 6 XBEE units I am able to get 3 of them working and communicating as either router/end device or coordinator, 2 of them will only work as router/end device and one works as neither.

Apart from the one which does not work at all, I have no problems uploading the firmware to the chips through the explorer and I am using the default settings for all of them.

The one which does not work at all when i try to upload I get one of the following errors; unable to find the modem, lost connection with the modem and failed to write to the modem.

Does anyone have any suggestions, I am lost.



You need to reflash the firmware on the non working modules using standard procedures.
Refer the following link, http://todigi.blogspot.com/2010/05/xbee-obituaries-xbee-returns-from-grave.html