deep is close and you might be able to solve it with a volt meter but an amp meter would be better suited. You will need to disconnect one side of the battery, set your multi-meter to I(amperage) and be sure that the red lead is in the correct spot(again with either an "I" or "current" next to it. Connect one side of the test lead to the disconnected batter terminal, and the other meter lead to the battery cable that was connected too it. Now the meter should start to read. All you need to do now is pull fuses one at a time till you see the current drop.
If you have the mach system the amps are known to go bad and stay on and create a load. If you do have them, disconnect them and see if it will start in an hour.