Gate remotes stopped working

[Steviev1]

Hi there, first time poster.

I have a Liftmaster 500 electric gate motor with I think failsafe photocells.

We went away over the weekend and come back, the remotes are no longer working.

Checked the CB22 circuit board and open and close led's are flashing red which seems to indicate photocell problem which tallies with the troubleshooting guide in the manual.

Now the remotes are still working because I pulled out the photocell plug on the CB22 and got them to relearn which they did.

Ive check the connections each end on the photocells with no issues.

Have the photocells developed a fault or is the circuit board having a moment?

Any ideas?

Thanks in advance