What are the odds that's what the momentary button is next to the toggle I believe controls the transponder bypass? I'd test it, but my RS doesn't power the starter anymore... I figured it was a programming button. I still don't know what unit I have other than being labeled DEI. But good to know it's something that's been done before
with Directed/DEI systems (really doesn't matter the model other than programming the option or bypass since they have been pretty much the same for the last 15 years) there is usually a small black push button (used to disarm alarms, or change programming options) and a small chrome valet switch (disables only the RS function)
this is the programming button
and this is the valet switch
the transponder bypass should not have any buttons that are easy to get to, depending on the model, it may have a programming button on the bypass itself.
when you say that "the RS doesn't power the starter anymore" do you mean that when activated that the parking light flash (only) once then all of the dash lights come on for 2-3 seconds, and then nothing happens after that?
because if that is the case, then that sounds like the transponder bypass is either not working, or needs to be reprogrammed to the car (if it is a learning bypass). it could also be a bypass that has a key in it, and if you (or any owner prior to yourself) have ever had the dealer program new keys and didn't remove that key to also have it programmed at the same time.
if its either of the last two, programming should be pretty easy of you do have two valid working keys and one of them is not a clone of the other.