DOWNLOAD: Droid 4 stuck fastboot fix (flash with RSD-Lite)
I had a problem with my Droid 4 today. I upgraded to Jelly Bean, and discovered I had lost root, despite using OTA Rootkeeper. I couldn't find a JB root tool, so I tried to SBF back to ICS and re-root there. Unfortunately you are not allowed to SBF backwards, so the flash failed.
Nothing was corrupt, the Jelly Bean install still worked fine. However since the flash had officially failed the phone now started in Fastboot mode every time...with a message saying that the flash had failed. To boot normally I had to hold power and volume keys and select normal boot, obviously very annoying.
As there is no Jelly Bean SBF yet, I could not flash that. So I developed a little RSD-Lite package to "spoof" a successful flash. If your Droid 4 is stuck in Fastboot mode, download the file above and flash it with RSD-Lite to get the phone back to normal boot mode. This will work whether you're on ICS or JB.