I looked at this for quite a while and although I've done a fair few mods with Forscan, I don't think its possible to get this one done there. There's a guy on YT who did it by adding a proxy device between the windows and the control mechanism: The Most Amazing Mustang Mod EVER!!
That's brilliant news - at least you got it all sorted and your new nickname will be Chilly-Balls! Its great you saved the $600 but it is fun and satisfying doing it yourself anyway 😜
Damn, sorry that bottom blower replacement didn't resolve your issue. Yeah those T50 torx bolts were really in there - I used a breaker bar to get them loose. You should be able test your old bottom blower now its out, with a multimeter.
Another good video from the Ford Boss on replacing the blower: 2016 - 2019 Ford Mustang Heated Seat Motor Replacement - SSM From Ford Didnt Fix Original Noise (youtube.com)
Same here. Bought red VLAND tail lights in 2020 and they're still functioning just fine - I still have the white tail lights which I swap out for the national car (road-worthy) test (NCT) evry two years.
You don't need to remove the seat cushion either - the metal frame that the blower is attached to, can be unclipped and push back so you can access the two torx screws holding in the blower.
If you start the car and turn off heating/aircon (and the music 😄) turn on the seat cooling to full and see of you can hear the seat fan blowing . . I couldn't previously but now the fan in the seat can be clearly heard.