You may need to put the battery on an automotive charger set at 2 amps rather than a trickle/maintainer charger now that it's flat. If you don't have one, pull the battery and take it to an auto parts store and they will load test it for free(and charge it first) It should still be good but they have been known to go bad with an internal short. How old it the battery?
Also pull the spark plugs and make sure there is not fluid in the cylinders, gas or coolant as that will make it hard to impossible to turn over. If fluid is present, turn over motor while plugs are out to expel the fluid, put rags over the plug holes so it doesn't shoot out all over the things you don't want covered with it! (if the bike is pre 97 turn kill switch to off to kill power to plug wires.
The starter may need pulling and a good cleaning.
Also pull the spark plugs and make sure there is not fluid in the cylinders, gas or coolant as that will make it hard to impossible to turn over. If fluid is present, turn over motor while plugs are out to expel the fluid, put rags over the plug holes so it doesn't shoot out all over the things you don't want covered with it! (if the bike is pre 97 turn kill switch to off to kill power to plug wires.
The starter may need pulling and a good cleaning.