I'd say it's a broken switch if it wont stay latched. I presume the machine turns on when its held down?
You could try a new switch, very cheap on here or ebay. Undo the torx screw behind the switch housing, remove the switch housing, being careful to flick the plastic tabs out of the back of the housing (from behind where the handle sits.
You will then see the switch, which just sits in a moulding. Remove the two brown wires from it, connect up a new switch then test. If you are competent enough with electrics, and the machine is still 'dead', connect the two brown wires together with an appropriate crimp and plug in. Should run with the power.