I have tried this: http://community.cambiumnetworks.com/t5/ePMP-Troubleshooting/Recovery-of-flash-corrupted-ePMP-devices-caused-due-to-power/m-p/54712
But that seems to be for older firmware. It did not work in my case but you can't extract anything from the .img file for firmware. Is this still a valid procedure for 300 series radios?