One key has the red led light flashing on all the time.

I think the switch which activates either open or close button on the PCB needs replacing.

What are the options for repair or replacement?

It can be repaired or you can purchase a new one from ebay and then you must recoding it.

This an old thread, but it still has some useful info in it, and you might even consider the upgrade to 3 button fob. If not, the basic principle is the same without the 3 button fob, just a replacement 2 button unit.

 

Thanks will pursue options.

I'll phone the local diagnostic VeeW in Bristol, see what they charge.