Woke up this morning to the 'updates ready to be installed' for the latest public beta... clicked to update and it rebooted into a brick. 75% of the progress bar, beach ball spinning forever. Tried every option, cmd+s, opt whatever, shift, safe mode, internet restore, restore from time machine backup, nothing worked. Ended up the entire day down at the Apple store trying to get them to re-image with 10.10. At first they wouldn't do anything to help me as soon as they found out I was using El Cap but eventually they did the deed and set me back a generation forcing me to re-install El Cap beta just to get my latest backup off time machine. What a mess, not at all what i was hoping to do all day. Anyone else have issues with this latest public beta?