So I installed some system update that they sent me last night. When I restarted my phone this morning, it just says "Firmware Update: DO NOT UNPLUG the USB connection until the process is complete." When that screen showed up, my phone wasn't even connected to anything. So, I plugged it in via USB to my Mac, and the screen hasn't changed at all. The meter on the screen still shows 0% of the process is complete. Do I have to plug it in to a PC in order to finish the update?