Put the battery on a trickle charger over night. Once done charging, check the voltage of the battery all by itself with nothing hooked up to it. Let it sit for 10 minutes then check it again. If it holds voltage, its good.
While the battery is not hooked up, check the resistance between the + cable and the - cable. It should be INFINITE. If not, the cables are faulty or not quite hooked up right.
My little push mower stalled on me a couple weeks ago. The air filter was major dirty. I cleaned it for use that day, but I have since replaced it with new. Check your filter.
