I had this problem as well - in my case, switching to channel 7 caused a reboot. Now my 5508 is in a continuous state of rebooting, unfortunately.
This is after allowing the unit to connect to the mothership and download almost 1000 channels/data.
Is there any way to somehow perform a factory reset before the unit reboots (reboot occurs after the fan starts and the final 'welcome' screen appears)? I've tried all the other suggestions found in the FAQs, checklists, etc. All assume that you can 382-Zones, etc., but I can't get there..