Hi,
Have you tried a TFTP recovery: http://community.cambiumnetworks.com/t5/ePMP-Troubleshooting/Recovery-of-flash-corrupted-ePMP-devices-caused-due-to-power/m-p/54712/highlight/true#M13
If that doesn't work, unfortunately the uboot is corrupted and the unit is not repairable.
Thanks,
Sriram