Cuts off when key released.

Cub Cadet ZLT L, 2014 Mower cranks and runs fine, but when I release the key, instantly cuts off. I have changed ignition switches and solenoid with no change. If it doesn't start for some reason, it blows the 20A fuse. Even removed voltage rectifier on a suggestion (what a bear to get out!!) with no change. Don't even know where to go next. Thanks for any suggestions.

Mower Model Number : 17ARCACA009
Kohler Engine Model Number : PS-KT735-3013

OK, pull the blower housing off and remove the kill wires from the magneto coils and try again
Engine runs fine = safety switch problem
Engine does not run = carb solenoid problem.

Do that & get back.
Please have a thought about your diction .
Remember your words are all we have to go on.
Obviously it is not running fine

So it cranks ( engine rotates )
Starts ( muffler goes bang more than once )
then stops, ie it is not RUNNING.

What is more important is what ORIGINALLY happened, when did it happen and what exactly did you do.
What switch did you fit & where did you get it from
What solenoid did you waste your money on and where did you get that from as well.

Can you read a simple wiring diagram ?
Do you have the one for your mower ?
If not go to Cub & get it so we are all singing from the same song sheet.

I had a similar problem, but with an older model, a 2165. It would start and run, then shut off. A mechanic friend helped me narrow it down to a rectangular-shaped doodad that didn't make much sense, but is called the voltage sensor. We cleaned the contacts, and it's been working fine ever since (but I did replace it, just to be sure).

I don't know if yours has one, but it may have something similar.