Unfortunatelly, I had the same issue here last night. I installed this update on august 12th (updating went fine, without any problems), and the WDTV worked just fine in that periode of time, until last night.
We were watching Netflix, when the WDTV suddenly started booting. After 10 minutes watching it looping in reboot, I pressed in the reset with a pin, that worked, WDTV booted normally. After filling in all the settings, I then used the Accuweather app and filled in some settings here, but there it went wrong again: device began booting (out of nowhere!), and ended up in a reboot loop, again…
Tonight I will try (with a pin in reset) to flash the device to the previous firmware, hope that this will help. If it does, I will not re-install this new firmware again, what a shame this is! Device totally screwed up with this new firmware!
If flashing back to an older firmware doesn’t help, I will use RMA at the store where I bought the device.