Yes a mechanic replaced my flex plate and backed it out of the garage seem to be something up with it as I was pulling forward got up the street like a block and a half and there was no transmission at all.When you put into Drive the dash light says neutral for 45 seconds and then Will Say Dr., Will not start in Park and less you play with the shifter otherwise have to start in neutral

 

Sounds to me like your mechanic botched the job.