I have a 7 speed, 42 inch cutting deck troy built pony mower with a 17.5 briggs and stratton engine bought in 2005 model # 13AN779G766. When you turn the key nothing kind of like the battery is dead. I've replaced battery, made sure all connections are still connected, check fuses that I could find, and made sure that blades are really disengaged. Of course have done everything that you have to do to start it (brake, blades, sit on seat, etc.). Wondering if anyone had any ideas. Thanks.

Smart move checking the many safety switches. They are still high on the suspect list. Try to get your test probe into the switch harness and check for continuity at each switch. Possibly the ignition switch went bad but I'd check the switches too.

You will need a volt meter and set it to DC volts
-Check the battery for 12.5 Volts
-Check the cables attached to the battery for the same voltage checking for good connections
-Attach the positive side of the volt meter to the + side of the battery and the negative side to the engine block, Still got 12 Volts? If not the ground from battery is bad.

-Now keep the ground on the negative side of battery
-follow positive cable to the solenoid and hook volt meter on the cable going TO the starter coming from the opposite side of the solenoid.
Turn key to "start" position you should have 12 + volts

YES-Check the same way on the starter motor where the cable FROM solenoid connects, If less or no voltage then cables or connections bad, If good voltage then starter is bad

NO- Take positive lead from volt meter to small wire going to solenoid and test for 12 Volts with key in the "start" position, If no voltage to small wire safety switch is telling it not to crank or ignition switch is bad (rare) If it does have voltage the solenoid needs replacing (common)

Hope it helps,
.Don