MODEL 13AVA1CS056without the full model number from the serial tag (usually start with 13) it is only a guess but it can either the PTO or brake switch or even a broken wire.
First make sure you haven't forgotten to turn the PTO off.
sorry this is my first riding wower and not great with electronics not awful eitherEvery switch simply connects or disconnects wires
They are all simple switches and apart from the engine plug are all simple blade terminals
Thus you make up some jumper leads with a blade on each end to bypass the switches 1 at a time
The exception is the seat switch but Cub do not use the "tamper proof" ones that Husqvarna does .
Since this is your first rider, you have to be seated on the mower seat before it will start. The seat switch is under your seat. If you get off without setting the clutch and then the brake, it will cut off.. next check battery connection. They get loose over time. As everyone else said make you are not trying to start it with the blades engaged.. Here's one for the future you may run into. The belt comes off and you remove the deck belt cover and maybe you bend the belt tensioner belt keeper to get the belt back on,,,,, not a good thing. It's best to use a 9/16 open wrench and loosen but not all the way, just enough to raise the tension pulley to get the belt back on and then retighten. I tried twice to force the belt into the tension pulley and finally figured out that was a mistake.I have tried everything new battery , tested starter , new solenoid and ignition switch still wont turn over at all.