I am having a similar problem with my MK7 fiesta key fob but unfortunately there does appear to be some damage to the PCB inside of it which is most likely why it has stopped working.
It still starts the car and unlocks the door manually but wont work remotely.
I was wondering if it would be possible to program a new untouched fob the way that is mentioned above? as the blade is working fine i could but the old blade on the new fob (which would almost certainly be cheaper than getting ford to do it) :)
Thanks for any advise you may have