Electrical gremlins, need pointed in general direction

Do you have a hand held meter?

The first part of this would be to check the batteries and see if they are charged and their viability. If no one knows how the cut off switch works, there is a good possibility that the batteries have been drawn down.

You need to break this down into stages of diagnosis rather than, "OK, the batteries are good, why does the generator only start when I push this ?"