I'm not sure what was going on here. It was very hot in the room, the Moto G4 plus I was using has been a bit glitchy after an update and I latterly noticed that the SD card was maybe too slow for HD.
I've since done a factory reset on the phone, only loaded the essential apps and replaced the SD card with the fastest I could get. The ambient temperature is also a bit lower now.
This is just a simple video showing the replacement of the tactile switches in a common Ford keyfob for a Transit van. They start to fail over time and then people tend to press them harder and harder to try and get them to work. You can buy replacements switches on eBay and they are fairly easy to remove and replace.
Both keyfobs worked fine once programmed into the van. For a 2004 Ford Transit you program the new fobs by getting into the van and closing the doors. Turn the ignition key from off to the first position eight times in quick succession, leaving it at the first position. The locks should cycle. If they do then press the open button on each of the keyfobs you wish to use, one at a time. Each time you press one the locks will cycle. Once finished, turn the ignition to off and the locks will cycle once again. The keyfobs should all now operate the doors.
Note that lithium button cells tend to still read about 3V even when they are near the end of their useful life. The best way to test them is to use a meter set to the 10A or higher range and very quickly dab the leads across the cell to see what the current peaks at. It should be a few hundred milliamps at least. Only do the test very briefly. Some cheap or old batteries may not be able to power a keyfob reliably if at all.
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