Totally unrelated story. This happened to me last Saturday. I just installed a water pump into some kids Porsche 944. I charged him $180 ($800 job if took to brick and motor shop). Took 3 hours. Fixed a bad vibration and running issue from someone else's timing and balance belt install. I drove the car around the block and the car ran great. The kid came over to pick his car up.
We took his car for a test drive and he was fanatic about the vibration issue was gone. He brought me back home and he turned the car off, it started smoking and then it caught on fire inside the dash board area. My quick tiger like reflexes, I grabbed the water hose and extinguished the fire.
I did not do any work inside the car but I was freaking out because it happened in my drive way. Was it my fault?
Anyway, I had to put any suspicions down that the kid might have had so I broke the dash down and try to diagnosis the cause of the fire. The wire harness from the Turn signal switch to the ignition switch harness had been burnt up. Took the turn signal switch apart and saw the problem.
When he turned the car off, he was so ecstatic about it running great, he exuberantly flick the keys off causing one of the keys to be inserted into the space between the turn signal switch and the wiper switch. The metal key provided a short that started the fire.
So, the morel of the story is not to jump to any conclusions until all of the facts are disclosed. The OP was so vague in what happen, No pictures, no follow up pictures. The remote Start should have been fused and if short was to ever develop, it would blow a fuse instead of smoking up like it did. We just don't know the facts before ostracizing his mechanic.