I have a 2000 Bayou 220 that gives me the buzzing from the solenoid when using the ignition button. I have replaced the solenoid, starter and battery twice (thanks to a mechanic that stated the previous New battery was no good) with no change. It appears to be going to ground when attempting to start, drawing down the battery. The mechanic used his jump starter to show me that the battery was bad, but I now realize it has continuous power supply to start (my ignorance).

Any ideas on where to begin?