OK SG,
This forum goes like this
We ask questions and you provide the answers then we ask some more
When we know enough we will give you our best diagnosis
I you want to get a lot of instant replies of which 99% will be wrong then there are lot of other forums where the replies are all about the responder pushing their pet problem
For starters we need the full model & serial numbers of the mower so we know exactly what we are dealing with .
Next thing is "died" is just not good enough .
A fuel related cause will usually be associated with some engine speed changes, smoke or funny sounds
An electrical problem will be like you turned it off .
And what you were doing at the time will rule in or out mechanical things like a branch stuck under the deck .