Check the battery voltage
Inspect battery terminals and cable connections
Verify the starter relay and fuse
Listen for a click when turning the key
Test for voltage at the starter solenoid
Perform a voltage drop test on the starter circuit
Tap the starter lightly and retest
Bench test the starter motor
Check starter ground connection
Inspect the flywheel or flexplate engagement
Test starter current draw with a clamp meter
Replace the starter if it fails the tests