Troubleshooting:

If you get a click or nothing at all while attempting to start the engine, first verify with a voltometer that the battery has at LEAST 12.4 volts and is fully charged. If you just put the battery in and did not properly charge it, it will be drained. Bad batteries often show 'fully-charged' on a charger but will have dropped a cell, and show less than 12v.

Next, take the spark plugs out and attempt to turn it over by hand. If it is locked up you either have pump or engine damage. Take care of that before going further.

If it turns over by hand, put the spark plugs back in. Expose the starter relay (solenoid) and jump it with a screwdriver, wrench or other similar metal object. If it turns over, replace the solenoid. If not continue.

Use jumper cables from the PWC battery directly to the starter. The positive goes on the stud/nut out the side, the negative to one of the rear mounting bolts. If it turns over, inspect every connection for a loose bolt/corrosion, and/or replace your main neg/pos cables on the ski.

If it still does not turn over, replace your starter.