maybe try printing out some of this site to show him what other people who have gone through this think. My experiences are that dealers NEVER stand behind stuff. they alway find some reason to blow it off and blame it on anything and everything else.
I would also ask that if perchance they DID bleed it wrong, could this have happened. That way you at least have a possible discussion about it. if they say it couldn't happen this way, get a couple of other opinions that say different. Now at least you have the grounds for an arguement, whether it be in the dealership or the small claims courtroom The way they operate service depts. at dealerships and the way they abuse the technicians they are probably not about to do anything willingly. Don't spend too much time time arguing with the service guy. go to the top, and make them believe that you mean business, know what you're talking about, and it is in theire best interests to rectify this problem without things getting litigous. at least maybe they will cut you a break on cost. unfortunately, their break is probably more than you could get an excellent mechanic to fix it for.
be polite and state the obvious. it worked before and then you did something to it , and now it doesn't work anymore. Also, don't try to convince them that you are a total expert in these things. It might backfire on you and they come back saying you should have know the risks and so forth.
"it worked before and now since you worked on it it doesn't work anymore. are you going to stand behind it or not" small claims courts usually try to split the costs onthese type of things. Dealers don't usually like to go there. If when you get their final no, file claim and see if they change their minds about helping out.
are you sure thatis it not just a sensor thats making the light come on. this does happen and they're pretty cheap. maybe it's just not in right?