You can try to get into the bootstrap and recover the unit. I've seen the firmware get corrupted before and the unit fails to boot correctly. You'll need to setup a TFTP server on a PC and copy over a new firmware. Here is the write up I used when I ran into this:
Do you happen to have the original firmware? I've been trying to hunt it down to no avail.
So i notice the site says 12.2.0-SA should work on my router. It doesn't boot the router just enters a boot loop.
I'm curious as to why, because everything I have says this firmware should work.
I do get a message on the show version. I'll have to pull it up when I get back tonight and post it here but it looks like a code failure.