I believe it should be possible to manually lock and unlock the door if it is a wiring issue. I think it may be a stuck actuator. The price to fix it seems steep though, in my book... Should be give or take a 1 hour job plus parts cost. Just my 2 cents.
1998 Xedos 9 2,5 MT (5-speed)
2000 Xedos 9 2,5 AT
2002 BMW 530i Touring stickshift
Originator of the Mazdaworld Old Boys Team!