Could well be , there's not a huge amount of components in an oven to fail
First thing to do is stop throwing money at it until you know what's wrong
Second thing is to disconnect the fan , make sure the wiring isnt going to touch the oven casing and turn the oven on and see what happens.
If it's not the fan then you will have to fault find with a multimeter as you have an earth fault somewhere
Does the grill setting on your oven turn the fan on?