Hey,
I recently shopped out my bsd and now for some reason mist multiball is screwed. When I run the test, everything seems good until the ball goes back into the right side. The gate lifts, ball goes in, gate lifts again and drops the ball. The test shows a fault and says only "power failure"

anyone know what the deal is?

There are 2 sensors for the ball on the right side, short range opto senses ball in it's right side nest. And long range radio frequency sensor beam from left to right senses ball is knocked off the magnet.  I would systematically test those sensors fun tion, maybe in switch test. My bsd also used to
drop ball and reload repeatedly and eventually I cleaned and freed up the gate actuator and bent the gate down slightly. In my case the gate didn't lower enough and the sensor didn't pick up the ball. Minor adjustment and you should check that first. I cannot duplicate your tests to advise as my MPU doesn't go into test mode.

ive been playing around with it and i think i have a problem with the opto board or the connections, while testing the mist optos several of the other optos went out (ball poppers and castle lock) then they went back on. has anyone had a similar problem or know how to fix it? i had workingpins over yesterday and he didnt know enough about the game to fix it off hand. i think i might have pulled a wire partially out of a connector somewhere while disassembling it but im really not sure.

SOS

Cold solder to connector that powers the opto board. Check if the led located on the board is lit.