If the starter does not rotate, then first of all check if there is voltage at terminal 50 of the starter solenoid starter. The voltage should be at least 8 V. If there is voltage, check the starter circuit. Whether the starter operates at full battery voltage can be set as follows.
Do not include gear. Turn on the ignition.
With a wire with a cross section of at least 4 square millimeters, connect terminals 30 and 50 on the starter, see section «Checking and replacing the electromagnetic starter».
If the starter fires, then the damage is in the starter lead wires. If the starter does not work, it must be removed and checked.
Check condition. Connections must be secure and not oxidized.