I own a 2002 saab 9-5 aero. When I banged on the starter yesterday it started. Today the engine won't even crank. I went to the store, it was a Friday. I got a boost and it started. Got the car home and shut it off. Tried to start it again and it wouldn't start. Adjusted battery clamp and it started right up. The next day car started right up. Went out and came back home. Next day car wouldn't start again. Had the battery tested, was told the battery was bad, so I bought a new battery. Put new battery in and car still woudn't start. Banged on the starter and car immediately started. Today car won't start at all
Did u check the alternator charge rate, is the car a automatic or a manual shift? Did u check the condition of the positive battery cable? If peeling or cracked u will need to replace said cable before going any further, post back with info.