Topfield 5800/Troubleshooting/Reboot Cycle
If you are stuck in a reboot cycle then the most likely problem is a rogue TAP. Stop TAPs from loading by holding down the '0' button on the remote while the Toppy starts up.
Another possibility is a problem with corrupt Settings. If you are stuck in a reboot cycle then you cannot do a Factory Reset but you can blank the Settings by flashing EmptySettings using the failsafe mechanism. Note that after applying this you must perform a Factory Reset as soon as possible, once the reboot cycle has been fixed.
Finally, an incompatible firmware patch may be causing the Toppy to crash as soon as it starts up. Re-flash a plain firmware using the failsafe mechanism.