Shut off while driving will not start?

Just bought this car and after a few months she stopped running on the freeway.
My mechanic determined it was my timing belt. Had him replace that. Also threw on my valve cover gasket, fuel filter, new plugs. Ran okay for about a week then just didn't want to start. He came to my work to try and get it started one night and had me crank after and during spraying what I believe would be starter fluid and my whole air box exploded and caught on fire. I have a few questions. 1. Could that have been caused because of the starting fluid? Positive on battery not being covered? Fuel pump shut off switch. Can I use some sort of glue on it, or does it need a new box? He came back to look at it and did not know what to do. Said something about maybe the camshaft and crankshaft sensors? Any insight would be greatly appreciated.