Black box needs to be mounted outside! Very surprised they recommended the door to be mounted like that for just the reason you experienced. A small overhang to cover the box from direct weather or some other cover would have done the trick.You were given bad advice.....very sorry your losses.
I love our door...it developed one small glitch....when it would close at night it would close then re open after a minute and then re open a third of the way and close.no big deal but I emailed them and the electrical engineer called me and sent me a new board and now it works perfectly again...