Updating the firmware always comes with some risks in this. The real procedures for updating the XBee firmware are kind of complicate if you are new to this. You might encounter any unexpected situation while updating the firmware. The XBee may not working after doing this. The updating process may interrupt by any reason and cause trouble. Please refer to this tutorial how to troubleshooting , then use X-CTU to give it a try.
Step 1. Connect XBee to PC with USB Adapter
Step 2. Click on the correct serial port , set the right "Baud" and API Mode(its off in this case)
Step 3. Click on Test / Query and you should got this messge
Step 4. Go to Modem Configuration and click on "Read"
You will get current Modem type , Function Set , and Version. It also shows all the current parameters in the window.
Step 5. Change the Function Set to API mode , and the Version for this Function Set will change to the latest one automatically
Step 6. Modify the BD - Baud Rate to "7 - 115200"
Step 7. Check "Always update firmware" then click on "Write "
It is programming after click "Write"
Step 8. If you see this window , click the reset button on the XBee USB Adapter or short the fifth pin to the tenth on XBee to continue. Else just ignore this part.
The error message from Test / Query , you might see this. Since the Baud Rate were set to "7 - 115200" with API mode turned on in Modem Configuration. I got this message from setting 115200 and check API mode in PC Setting.
Change the PC Setting to the original 9600 (API still checked) , then it can to the XBee again like this message showed. After it's working , go back to Modem configuration , uncheck "Always update firmware" , and modify Baud Rate to "7 - 115200". Finally click on Write , then the problem is solved and everything back to normal !
Step 9. Go back to PC Setting , set the Baud to 115200 and check API mode. Since the function set selected the API mode , so we have to enable API mode to talk to it , not the AT mode. This the final Test / Query.
It means the firmware upgrading is done , then test it to see if it works properly.
You can also try the button "Restore" at this moment. Before you hit the button , check the status of XBee first. Right now it is 115200 with API mode enable , the modem type is XBP24-B with function set "ZNET2.5 COORDINATOR API" , the version is 1147.
After hit the "Restore" , you can talk to it again when set Baud to 9600 in PC Settings. Which means it only restore the parameters to the default setting. If anything bad happened while updating the firmware , this button won't restore it to the factory status. So , always update the firmware with cautions if you have to do it.
You may wanna have a look at the tutorial about using XBee with Arduino , you can find it in this website.