What could be the reason my car wont turn off? on 1996 BMW 328is

I just got the windows tinted on it Sat. i went to pick up the car Monday from the guys shop. The car was in garage the whole time he started it up and moved it saturday afternoon. it sat for a day, he went to start it Monday to move it out, It would not turn over checked the battery its fine lights, and radio come on. What could be the problem?

Asked by for the 1996 BMW 328is
you need to clarify your issue; you say it won't turn off and then you say it won't start---which is it???
1 more answer
1. maybe your immobilizer is the problem based on the wear on the key, ews, or even the dme/ecu may be faulty

- dme's should be checked for water damage
- find someone who can disable the immobilizer

2. even a correct key will sometimes be faulty, so ignition switch will keep car running or somtimes keep it from cranking by disengaging and turning and turning and ...

- keep turning until it re-engages

3. alarm systems can cause stuff to NOT work even if the dash is lit bright

- check to see if the alarm system is silently activated preventing start

3. BMW's are great looking and great driving cars, but with horrible reliability

- sell the car asap (to a BMW dealer)