Grandson's troy buit bronco with kohler courage 20 engine (sv600s) died after he had taken a short break...... would not crank nor make a sound when he tried to re-start it,,,,, battery checked at 12.4 volts (lites are working). When he hooked jumper cables to starter it cranked as usual, then nothing when removing cables... I'm thinking selenoid (even though it made no "clicking" sounds).... Any advice,,directions greatly needed!!! THANKS