If you (force) update on an unlocked HTC phone, you are not likely to get any problem. However, if your device is carrier locked, then, you will need to follow this guide to unlock your device. First, you need to make sure that you are running NoDo.
Now, first you will have to unlock your windows phone. Then, download HTC Connection setup on your phone’s marketplace by searching for ‘HTC connection’. Also, download the custclear.provxml file from here and put it into the windows directory on the phone. You can use windows phone device manager or Touchxplorer.
Then google for how to get mango beta on your phone. Immediately when Mango boots on your computer, start HTC Connection. Your phone will be unlocked.