Newbie Help with a JD Z225 Cranking No Start

First post, found the forum through google searching for my problem.

Last weekend I got a JD Z225 started that hadn't ran for a year, but was "professionally" serviced before it sat. I replaced the gas, battery, and spark plug and it fired right up. I mowed for about 10 minutes and then left it idling on low throttle to run through any fuel left in the lines/carb.

As I was working on repairing another small motor my Dad (yes, I'm throwing him under the bus...) went over to the running (low throttle) mower and attempted to engage the blades without increasing the throttle (he didn't know better even though it is written right next to the mower engage switch). As soon as the mower attempted to engage the blades the engine stopped running with a nice puff of black smoke out the exhaust.

I tried to get it started again, checked fuel and spark, tried some starting fluid in the intake, but no luck. Engine cranks, but doesn't start.

What should I check next? If anyone can give me an idea of what to search on the forum I'm happy to do it to save everyone's time if this has been covered before. Thanks!

check fuses

Pull the blower housing off and check the timing key in the flywheel.
A sudden abrupt stop can shear the key so the spark is at the wrong time.
IT is a fail safe idea that has been abandoned.
THe old keys are alloy and the recommended replacements are steel.