Temporarily unplug the engine connector with the Blue & White wires. The White is the engine kill wire. When grounded, it kills the engine. (Blue is the alternator, so make sure it doesn't short to anything) IF that "cures" the problem, then we know the White wire is getting grounded somehow. Either a bad switch, or worn insulation on the wire itself. Inspect the wire where it touches the chassis etc., to see if there are any bare spots. Note, with this wire disconnected, the engine won't "kill" normally. You might also try unplugging the pedal switch to see what happens. According to the schematic I have, it doesn't have anything to do with cranking the engine, which DOESN'T make sense. The "module" has me stumped, since the schematic doesn't show what it does. Just the plug with Blue Red, Green & White wires. You could also try unplugging it, or wiggling the connector. Sorry I can't add more insight.

If you have the tools, I would check the battery and charging circuit. If this circuit is working you would not be able to run the engine until the battery was drained. You could run out of gas, but if it is working not drain the battery. Note: in the future, when the standard function to hot stop the engine, you can stop the motor by shorting the spark plug to the block with a screw driver. I have done this numerous times with small engines. In fact, on some of the older engines there was a strip of metal attached to the engine,, that you would push against the plug to stop the engine. I am new to dual cylinder engine, so you may have to short both plugs at the same time to stop that type of engine.

Seat switch is open when seat is occupied. Seat switch closes when seat is vacant. Closing the seat switch connects the magneto kill wire to ground, stopping the spark production and causing the engine to quit running. The clutch switch is part of the interlock circuit and WILL permit the engine to run with the seat empty provided the clutch/brake pedal is down. But since you connected the seat switch wires together, the clutch switch is the last switch to close and now it acts as though the seat is empty, even when the seat is actually occupied.

Your post isn't real clear. The safety system is designed to shut off the mower when the clutch isn't let out if it doesn't detect your presents on the seat. Seat switches do fail plus I have seen on your rider where the seat bracket or switch bracket (slips my mind exactly) was not assembled correctly and the switch wouldn't activate for the owner- but could for a bigger individual. If it is able to run, but only run slow- does it feel that the engine is lugging down?