I don't have one of the Bachmann packs, so I can't be sure, but a friend's unit used a slot head screw that had a ridge across the slot to prevent a regular screwdriver from fitting the screw. I was able to notch a screwdriver with a cutoff disc chucked in my Dremel tool, which worked fine, and still functioned as a normal screwdriver.
I know that MRC used security screws in some of their power packs that were like a Torx allen-headed screw which had a pin that stuck up in the center of the socket in the screw head, thus preventing the use of a standard wrench. I had some luck removing those using a small flat screwdriver which would wedge in the socket allowing the screw to be turned. on a couple of them, the security pin snapped so that an Allen or Torx wrench would work. Later, I discovered that Harbor freight has two different multi tools with the Torx security bits whose ends are drilled out to accommodate the security pin (proper tool for the job).
Once inside your power pack, look at the power transistors to see if they have a number, if they do, they can be identified by a good electronics parts house and replaced with the correct crossover part. Also check the circuit breaker, it may be bad.
good luck,
Bill in FtL
