I have the exact same problem was working fine then next time I turned it on Flashing lights, so I updated via the Ipad app and it said it updated successfully. But when i turned it on it would not come out of recovery mode and still said it needed the latest update even though it was already updated. I then updated it with the PC and same issue, after finishing the the update successfully it then rebooted back in recovery mode (all 4 lights flashing). I tried factory reset with no change. I then decided to back date the firmware to the previous version 2.10 after that all 4 Tone Lights Solid and Faint bluetooth light. tried resetting and updates procedure no luck. Got to play through it a total of about 20 mins sounded good when it worked.
Just got this Amplifi 150 from Line 6 yesterday!