Make sure the battery is fully charged.
Turn the crankshaft with the starter and make sure that the starter runs evenly, without extraneous noise.
If the operation is not as described, check the voltage between terminals S and B when the ignition switch is in the START position.
Rated voltage: more than 8 V.
If the voltage does not correspond to the nominal, remove the starter and check the traction relay and the starter motor.
If the traction relay and starter motor are OK, check the wiring, ignition switch and start inhibit switch (for models with automatic transmission).