Quite a few of us are in a reboot loop since getting the update overnight....
This morning, all my 622 did was sound like it was rebooting.
The TV1 light would come on for a while, then eventually all the lights would flash on then off, the fan would shut down and then power up again and repeat the process all over again continuously.
No output was going from the HDMI connection to the TV.
Tried a couple hard reboots (hold power for 10 secs, and even remove power for 10 secs), but it kept doing the same thing.
Eventually I gave up on it and headed into work. Hopefully the update didn't brick it.