The plastic hinges have a pin that pushes the lid switch. It could be that the pin has broken off, or the switch has failed.
You should find the centre of the hinge and if you push it, it’ll make a click.
To lift the top, you need to take the metal plate off the back of the control panel. The hob then slides forward and lifts up. With the control panel, be careful as the plastic end pieces are very brittle by this time.
The lid switch is secured in place by the hinge. Again, be careful with the hinges as the plastic can be quite brittle by now.
Depending on what’s wrong, I may have hinges or a switch spare, but I’d really need to dig into my parts to check.