My 7.7 is stuck in a Downloading loop and I'm glad I bought it from Amazon UK who have agreed to replace it. I've tried holding the power button down until the downloading screen disappears but it re-appears almost immediately. The 7.7 is less than 30 days old and I've just done one official OTA upgrade when offered it. I've Googled for help but this problem seems rare as I've not found anyone else with it.