I had the Marshmallow update OTAed to my phone yesterday. The handset, which is 100% stock, is now bricked. It can only get to the fastboot screen. Factory Reset does not work. It cannot boot to recovery as the recovery image fails validation. Other people on XDA Developers Forum are reporting the same issue, all on 100% stock handsets.
My advice to Droid Turbo users is that you carefully consider if you're going to take this OTA. I suggest you wait until VZ have investigated and fixed the problem.
Marshmallow was pushed to my Droid Turbo last night.
I elected to install it later in the morning. About 20 minutes after selecting installation, it rebooted to the M screen (with the Motorola logo in the center and the android logo at the bottom of the screen.) It was hung in that state for 2 hours before I decided it was not working.
Instructions to enter Safe Mode do not work. I just keep getting the M screen.
Is there anything else I can do, or is my phone bricked?