How are Alcohol monitors (Blow & Go's) wired into the ignition???

Brother had a court-ordered alcohol monitor (Blow & Go's) put on his Ford conversion
van, well he did his time, and had it officially removed couple weeks ago. Right from
the start before leaving the garage, he noticed one of the doors was "dead" (no locks,
window action), was working when he drove there, well they admitted & fixed the
problem, brother drives home, parks van, next day comes out and now it won't turn
over, just "clicks" according to him, I asked if he made sure battery was up and he
said he tried a couple battery's and even trickle charged the one in the van, with the
same results. I'm guessing there's a crap splice job somewhere??? If it was me, I
would tow it back to that garage and make them fix it along w/ the tow bill, but wants
me to look @ it. He is 70 miles away and I'm trying to gather as much info as I can
before the trek. I have no idea how these things are wired into the vehicle, but know
about car wiring because I installed car alarms for years, any insight is much
appreciated ;)
Thanks