By any chance do you have a spare key? If you do a search for remote start you will find that in the key fob is the sensor(?) that communicates with the anti theft sensor(?) in the dash that allows the car to start. When a remote start is installed the spare key has to be left permanently under the dash within close proximity to the key location to start.

So maybe when changing the casing your key unprogrammed from the car. If you have a spare then try spare, if not then search programming extra key and follow those steps to reprogram your keys. Good luck.