OK- - - - -now monitor the voltage at the battery posts (not the cable clamps) with a voltmeter as you try to put a starting load on the battery. If it drops to zero, or a very low reading, the battery is either discharged, or it has an internal open circuit. Sometimes a battery can develop an open circuit that allows it to register voltage when not under load, but it will go open circuit as soon as even a slight load is applied.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!