Electronic – XBee wireless module not responding any more

I bought an XBee-PRO S1 .. I built its serial explorer to be able to configure it through the PC, I’m using X-CTU to configure and test it at first it worked well,I made test/query successfully many times I tried to write a modem configuration to it .. but each time ended with a failed message, through this the chip was still responding to the test/query, and the terminal command "+++", but trying to configure it 3 or 4 more times it stopped responding, well, I figured I was wrongly configuring it, as I didn't use the reset to reset the chip before writing the new configuration to it .. then i fixed my explorer circuit, and tried using a reset button, it worked one or two times, and a progress bar appeared, but the process failed too .. now the XBee isn't responding any more for any of what I did before .. I searched, and found many people facing the same problem ..

This problem happened with two modules in row …..

In short “I write +++ it responds OK , If started to configure say AT..anything , It stops & no respond , if I tried “+++” again .. no respond , it’s even not recognized by the X-CTU” …

I hope I can find help about what should I do to recover this XBee, and what mistakes did I do so I can avoid them in future ………

Update #1:-

I contacted the manufacture digi(dot).com

Support:
In order to change the firmware on the radio, the DTR and RTS lines are required. To resolve your issue, I would recommend either acquire one of our XBIB interface boars or you follow the steps outlined at http://www.youtube.com/watch?v=fxOqQZD-oaM once the DTR and RTS lines are connected using the proper level shifting.

As described in the product manual, the radio is a 3V device and is NOT 5V or RS232 level tolerant. You need to use a level shifter between the radio and the PC or some other Non 3V CMOS level device. Otherwise you will damage the module.

You can see a sample schematic of our XBIB interface boards buy going to http://www.digi.com/support/kbase/kbaseresultdetl?id=2118. However if you are not familiar with level shifting, I would strongly recommend acquiring one of our XBIB development boards as it will give you a known starting point to work from.

Me after the update :

Of course nothing worked from the support !

The behavior I noticed that :-

When I press the reset for a while (4 ~5 ) seconds , the CTS line in XCTU is lighted up(Green) ….. So ?