Welcome to the seadoo forum motor389. Let me get this straight. You have a new battery, you go to start it no beeps, no power in the cluster. The battery box is full of water to the top...what do you mean? Is the lanyard cap dirty? Use soap and water and be sure it is clean. Don't grease it or use anything on it.The battery feeds the solenoid direct and than a 15Amp fuse feeds the MPEM,(Multi Purpose Electronic Module) from the same post, on the solenoid. Check that 15 amp fuse. Make sure the ground is good that runs from the battery to the starter. I bet the electrical connections aren't making a good connection. Use a multimeter to test the 12 volt and ground circuits, not a test light. The test light could cause a electrical problem if you test it incorrectly. Check the connections I mentioned and get back to us. If it still doesn't have power, I have a couple other things you can look for.
Karl