Illinois

Curious, because I don't picture what could go sideways, other than the battery being toast.
I've had an EGO mower since the spring of '18.
I'm still on the original battery. (I've got extras, because I also have their snowblower.)
If it's the battery, anybody with a voltmeter can see if it's showing 40V. Checking amps is more involved, as an ammeter must be part of the circuit. But, an electrician sure would know how. So would any electronics hobbyist.
Come to think of it, a loose wire on the motor or the speed selector could render the mower useless.