87 RX-7 Won't Start

I have a 1987 Mazda RX-7 13b style engine non turbo, less than 60,000 miles. I recently had a clutch installed in my car at the same time the starter would not engage the flywheel, the mechanic told me I needed a starter due to the rust falling out, allthough I knew a solinoid (spelling?) Would most likely fix the issues I opted for the starter. The mechs messed up BIG time, first I had an leak in new gasket they claim to install on the exauhst pipe they removed, so one week after it was done I had it back for that, now a week and a half later the car is back, the car just quit getting off the highway, it started right up but died again, I parked it for the night and came back the next day, my wife saw smoke coming from the engine, that is when I noticed the MAIN NEG cable from the battery was not connected to the starter, it was resting against some sort of sensor that is rear and below in relation to the plugs, it appeared as if a small flame was coming from the front center of the part. I promptly called the transmission shop, they said to just hook it back up and see if it worked, no start. About 3 days before this happend my wife was in the car while I was in the store and the compressor for the A/C smoked out and fried, the system was working fine, just charged, full of refrigerant and about 2 years old(entire system) I had to cut the belt on the compressor after the car stalled out b/c the thing was frozen solid. The mechanic claims that there is no way that his unconnected ground cable would cause ANY problems to the A/C but could have caused a problem elsewhere causing the car not to start. I have talked to a couple mechs that say it could have but they are not sure, I work on electronics for radios but I am assuming that is is about the same for a compressor that if it is supplied power without a suitable ground that it would then dissapate the power as heat, sitting at idle and running then would overheat the thing causing it to freeze up like that, also I think that something is really messed up with the ignition system due to the lack of starting, it cranks great and I smell fuel but no start.
I also installed an alarm that is only a theft deterant, no anti start was connected, the mech mentioned that and said that that could have caused it, but the alarm is still fully function and never had any problems, it is connected to the door lock I installed, the NEG door trigger wire the NEG trunk trigger wire the curtosy light is connected to NEG door trigger wire, 12v constant to battery with fuseable link, grnd, parking lights, and 12v switched(spliced in w/radio) I also installed a system in the car with a 1/0 wire from battery to trunk. Of course the mech said that maybe the problem, although all the circuits in question have NOTHING to do with starting the veh. That was my first instinct as well though (alarm) since it was the newest electrical device, I unplugged entire system and fuses, still with no luck on starting. I am going to end this post, any further needed info lust let me know, any help would be great! Thank you in advance