Btw there is an earth wire with no connector in the kit, there is a threaded bolt under a rubber cover on the back of the head unit the earth wire can be attached to it with a small nut & washer.

Personally I'd attach the wire to the small screw near the brown connector instead. The rubber bung presses into the back of the dash to hold the radio in place, so if you put a connector onto its bolt, it will stick out a bit further and may make your radio stick out slightly from the dash.