John Deere GT235 18-hp Briggs

Depending upon what type of charging system it uses its most likely that the battery is cooked dead.

On most B&S engines with the 15 -20 amp permanent magnet alternator the voltage regulator is typically a small aluminum box about the size of a deck of cards mounted to one part of the engine cooling ducting. It will have two wires coming out from under the flywheel and one that goes to the battery or key switch.

They do fail to full on output at times and can boil a battery dead after a while.

When the battery has boiled off too much electrolyte its voltage can go higher than what the ignition system is designed for if its a powered ignition or had a solenoid powered by 12 volts some place that keeps the magneto active. Some also have a fuel solenoid on the carburetor. Too high of input voltage for too long could have burned that out as well and caused the fuel supply in the carburetor to be shut off.

Thats the basics of a most typical B&S engine and charging systems.

If you put a good battery on it and the crank it over see if you have spark. If so the fuel solenoid would be the next place to look.