Making resistance readings on a generator is pointless- - - -it will always read close to a dead short, good or bad. That's why there's a cutout relay. Take the generator to a rebuilding shop where they know how to check it out, NOT a big box place like Auto Zone. It will need to be dismantled and checked on some special equipment, including a growler.

Recharge the battery over several days at a low amperage (10-15 amps) until the specific gravity of the electrolyte is 1.265 or above on all the cells- - - -it will probably be OK.
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!