Have a 1996 Toyota Corolla. The key will not turn in the ignition. The key turns enough to go to aux power, but will not turn any farther to start the car. Any suggestions? Thanks!

sounds like bad/dirty ignition switch contacts. replace it

See if you turn the wheel and try to turn the key at the same time if it releases. We might get a free spot where the key should turn. The lock may be in a bind and pressure on it may release it.
Clean and lubricate the lock cylinder. Electric cleaner to flush the dirt and liquid graphite to lubricate. A substitute for the electric cleaner is a spray of isoprophyl alcohol.
You may also need to tap the assembly for the ignition switch to release the mechanical parts. See if you can get the cover of the steering column off to gain access to the ignition switch assembly.
Check also if the spare does the same, other wise the key may have deformed.

There is a 12 volt signal from the ignition switch to the starter relay ! Start by having someone turn the ignition to start and with a test light on the small wire at starter see if it lights up with the ignition cylce at start ! Second -locate the starter relay in the fuse block and swap it with another same style relay and see if it will turn over ! I believe the computer is behind the glove box on that year ! You can follow the large harness in the engine compartment to the bulkhead and that will tell you where in the interior the computer is ! Hope this helps !

try the starter solenoid or the starter relay....be sure all the starter/ignition fuses are good

have a new ignition put in or you can try getting another key made and tell them not to buff it

put key in ignition turn on then press alarm button to reset

press and hold the arm/disarm button or place key in ignition and start the vehicle.

Radio and lights can work with weak battery, too weak to turn starter.

Noise when shutting off maybe dieseling due to fuel mixture too rich or timing off.

When you say car won't start do you mean starter turns but engine does not start, or do you mean starter does not turn.

Try your fuse panel. You must have blown the ignition fuse when replacing the starter.

it sounds like either your having a short at the starter or the ignition switch is bad, I am leaning towards the issue being the starter, usually when the ignition switch is going bad there will be no click,