[GTP Dad]

There are a couple of issues that may be causing the issue. First check to see if you have fuel. Spray starting fluid into the throttle body while someone cranks the engine if it starts it is fuel pump related. If not then you need to check the ignition side. Make sure that the wires are connected properly and that the battery connections are good. Based on what you did to the car there is nothing that was done that should have caused the no start condition. Unless they gave you the wrong MAF sensor but that shouldn't stop it from starting. Make sure to check all grounds!!