Why won't by g8 start?

The tires on my 2009 Pontiac g8 went bad, so my car was left sitting for a month and a
half while tires had to be ordered, and an appointment set up for installation. When I
went to drive the car to the appointment, the car would not start. All lights and dummy
lights worked, but it would not turn over. For some reason I thought it was the battery,
but getting a new one did not help. Tried jump starting and it did nothing. We fiddled
under the hood and realized the ignition fuse blew, so we replaced and tried again. It
blew the next fuse, so we put a bigger fuse in and that did the trick. I drove to the
appointment, and it started when leaving, but died on the way home. All lights still
working at this point as well. Towed it home, and realized the mass air flow sensor was
smoking when trying to start. Replaced mass air flow sensor, but now the engine
immobilized light is on, and won't let the car start. What is going on, and how can I fix
it?