Thanks. I don't even get the car to recognise either remote. I put new batteries in a few years back so don't think they will help.
I had the unit open for another reason about a year ago and there were a couple of internal buttons (see photo). According to an instruction/installation booklet I found (and posted on here) for a similar looking unit, there are some internal options to add a new fob. I tried the option to add a fob from another fob, but that didn't behave as described, so even though mine looks pretty much identical, its behaviour is not.
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