I have encountered a really annoying issue with my HTC One. It is a completely new replacement unit, and ever since I started using it I've had problems with the reception. In the beginning it only lost reception for a short while, and then regained it. Now however, the loss of reception is almost always followed by an immediate reboot, and after this reboot the phone often will not allow me to enter any pin at all. It will just show a "no reception" symbol in the status bar and subsequently reboot again after a minute or so. This boot loop continues until the phone actually allows me to input the pin again, after this the phone will work fine for awhile until this looping business starts anew.
I've actually tried a whole lot of different roms and radio versions in order to try to solve this issue, but to no avail. I've also used an RUU to reset my phones firmware from the very beginning, but the problem still remains. I've also tried to swap sim cards, no luck with that either.
I've tried to check the logs after these reboots, and the only things that seem to have anything to do with this are the lines: "failure to start external modem" and "MDM common shutdown".
Am I out of luck here? Is there anything I can do in order to try to fix this myself?
I'm afraid that if I hand it in for repairs the shop won't actually experience anything wrong with it, since this happens so randomly, and just send it back to me with a service fee.
Help is much appreciated!