I have a problem with 7962/7915 set. The 7915 lost its connection when power cycled after working for several months. All lights on it stay orange now. I found that the firmware for both parts are not on the UC520. I moved the 7915 to another 7962 and it powered up and worked okay. I factory reset the broken 7962 and manually upgraded the firmware to a recent version. It didn't solve the problem. Any help would be greatly appreciated.