Estate rear bumper removal

[Freddydreamer]

Been hit from behind in a low speed car park accident and from an initial inspection it looks like one of the wires to one of the parking sensors has been damaged. When I started the engine I got a message saying fault with the optical parking sensors and now none of them work

2 questions

How do I get the rear bumper off? Taken out 4 screws and a plastic expanding pin from each wheel arch. Taken out 2 screws from inside each light cluster. Taken out two screws holding the valance into the boot well. Taken off the under tray on the right hand side. What am I missing as the bumper is still firmly fixed to the car?

Also if I solder in a new cable will the parking sensor system spring into life, or will I need to reset something?