I set the Modem: Xbee setting to XB24-ZB and chose ZIGBEE ROUTER SENSOR as the function set. While writing the new setting to my XBEE S2, I get the "cannot communicate with the modem" popup and was asked to reset. I did that but nothing seems to have reset. Now the associate light on the XBEE shield doesn't blink as before and I can not communicate with this XBEE S2. How do I get to toz reset and get the light blinking again (this is what happens on the working XBEE S2).