unlock door relay not working

Hi there, this is my first post here so I hope I’m posting in the correct section.
So my passenger and back doors don't unlock (from clicker and switch in the car), I can hear the motors in them, but they don’t unlock.
I took the car to the dealership and they said that the relay has a short in it and that they want to replace the entire power junction box by the passenger side. This is after charging me $170 to “reprogram the relay”, which fixed the issue for a day and now they want to charge me $1000 to replace the box!
Does it make sense to change the entire power junction box?
Any way I can fix this myself? I am studying electrical engineering but don’t have experience with car circuits specifically. I just feel like a $1000 is a rip off for a 2004 Mazda3.
Any ideas or documentation about the locks would be much appreciated.
Thanks