If you have access to the radios, I would highly recommend updating the firmware on all of them.
First, update to R13.2.1, then update to the latest release, R15.0.2.
Make sure you have CNUT v4.9 installed to perform the updates.
Once that is complete, see if the radios connect. R12.0.3.1 is the very very first firmware that shipped with the very very first 3 GHz radios... we have made significant improvements and changes since then. It sounds like this hardware may be very old.
Is this in the field, or in a lab/testing scenario? Are you sure the SMs can see the AP signal? Are the proper channels configured?
Were they all connected at some point?
If you are sure all of the configuration is correct, there is a possibility the hardware is no longer good, but I have never heard of a failure rate of this magnitude before. You did mention that there was no surge protection on these units, so if a lighning storm occurred, it may have affected several units.
Are these all being tested, where the other are working?
I ran into simple stupid because the Milage defaults to 2 miles. I was 2.4 miles. A two hour oversite. I tested withing that 2 mile distance of the tower, which woked but when I went back to the office to lab up it wouldn't work.