Heimanshu's idea is, of course, the best option, but if you're having trouble flashing a recovery, you might try this thread, hopefully it will re-install the JB update.
Failed to flash via fastboot. Tried to reboot and now I'm stuck on boot screen. I can't boot into recovery,only fastboot.
Tried to re-flash official cwm-recovery, but it stopped right after the progress bar came up..
The thread title sums it up. I am running cyan off of emmc. One day my sd card is popped out. When I try to push it in, it doesn't catch! Just slides in, makes somewhat of a click, and slides right back out.
So, I am stuck on this build, no...