Same issue here. I have 2 of these. The first one has some weird issues, but had no issues updating. It just had a lot issues with cec, lag, flicker on boot.
I got the second one to see if I had a lemon. I hooked up the 2nd one and it worked fine until I initiated an update. It update looped for about an hour until it looked like everything was good except no sound and it wouldn't respond to any remote commands besides volume up and down. I rebooted it and now it's just boot looping like you're saying. 1 solid and 1 blinking and then 7 solid and 1 blinking. Repeat. Going to return this to the store I think. I tried everything I could to unbrick it.
Tried factory reset button combo, non responsive
Tried USB firmware update, non responsive
Tried leaving it off for 10 minutes, no change
Tried leaving it update looping overnight, still looping. Seems like my second unit truly is dead