No Starting Condition on 1996 Buick Park Avenue

Vehicle is not attempting to turn over, fuel pump turns on lights, ac all turn on, Battery has been checked by parts store, starter has been checked by parts store. Vehicle will still not start. Please help.

Asked by for the 1996 Buick Park Avenue
An engine needs three basic things to start, mechanical integrity (the engine's components must be in synchronization with each other and the engine must be able to develop compression), the engine must get fuel injected into the cylinders (fuel must be injected into the engine ( there is a computer that takes inputs from many sensors on the engine, interprets these signals and decides when and how much fuel to inject into each cylinder) finally the engine needs spark to ignite the fuel injected into the engine, (the spark is also controlled by the vehicle's computer deciding when the spark arrive at the spark plug). If the components in the engine are not in synchronization due to a broken or "slipped" timing belt or chain the engine will not develop adequate compression to start and run properly. If any engine sensor has failed (crank angle sensor, camshaft position sensor, intake manifold pressure senor/air flow meter, coolant temperature sensor) any of these will cause the engine to fail to start by causing a loss of spark or fuel delivery. All these components need electricity to function, a failed fuse, relay, open or shorted electrical circuit could cause the computer, fuel pump or ignition system not to function. Unfortunately there are too many things that could cause your engine not to start to be able to pin point anything to specifically look for. Check for fuel and spark first.
2 more answers
check the crankshaft sensor, camshaft also see if the security light is flashing inside the dash
Try cleaning your positive battery cables..there are 2 together and they get corroded in between.