Battery reads 12.5 vdc already. Fairly new.
It's a 2012 (or so) model so no warranty.
Remember, it ran fine just a few minutes before. Until it didn't.
Running is different than starting. Don't guess; still check the cables. Better yet, remove, clean and re attach both ends of both battery cables. Just do it. You'd be surprised..... And with everything dead, it almost has to be battery, primary battery cables, or the main breaker fuse. I'll go farther than that below, but mostly just because this is a good chance to put down how a home mechanic should check things before going to the tractor shop.
It is rare, but a battery can have full 12.5 voltage and still not have enough amperage to turn a starter motor. To check this, leave the voltmeter on the battery while you engage a load - best would be a starter, but a couple of headlights or a large resistor would suffice. The voltage shouldn't drop much when the battery is loaded. This is what they are checking at "Batteries are US" when you take in a car battery and they run a load test. It's generally a free test.
Next step after the cables.... would be the breaker fuse....but you've done that. So do it again. THen, Double check that all the various safety switches are satisfied or bypassed. If they are all correct and the ignition switch itself is OK, You should hear the solenoid CLACK when you press the starter button.
When you you are satisfied with the cables, and switches..... the next thing to check is that starter solenoid just mentioned. It's the little can with three wires going to it that sits on the side of the starter motor. Part of it's function is to make a loud CLACK right before the starter begins to turn. There are two large wires and one small wire going to the solenoid. One large wire goes to the battery and the other large wire goes to the starter. The small wire goes up to the starter switch on the dash. When you tell the tractor to start, the wire from the dash carries a signal down to the solenoid that activates a relay - making a LOUD CLACK SOUND - as that relay connects the two large wires together internally. Now full battery power can pour into the starter motor to make it turn.
Starter motors last much longer than solenoids. Typically you will replace one or two solenoids in the life of a starter. The most common malfunction of the solenoid is for the internal contact points that carry the heavy current to burn to a crisp and then they become crispy insulators. The defective solenoid still makes a loud CLACK when actuated because it is slamming those high amperage contacts together inside itself, but the contacts cannot make enough clean metallic contact to send the needed current to the starter motor.
If you can take the solenoid off and apart, you can find those burnt points - they are usually copper - and clean them up with a small file.
Or just replace the solenoid on a bet. It's a half hour job done with minimal tools and they are inexpensive parts.
Once the solenoid is dealt with, it is on to the starter. This is when I lwould look around the surrounding small towns and see if there is a one-man shop that repairs starters and alternators. An old-fashioned auto electric shop. Generally tiny, generally messy. Starters are usually removed simply by undoing two bolts. All the wiring is to the solenoid. Disconnect and take it over to the auto electric shop for a rebuild. Usually that's $150.00.
And if that does not do it, then it's time to take out a schematic and your volt/ohm/meter and check if the ignition switch is working.
And if that doesn't do it, it is finally time to call the tractor shop mechanic. And if you can get him to believe you have done all these things above (and he is going to check for himself), then you have still saved yourself a few hours of of his wages.
Electrical malfunctions are the preferred mechanical shop problems. They are always completely logical, clean, and non-oily. They can always be fixed. It's like being paid to play a computer game.
rScotty
