Rear parking sensors playing up. Orange light showing

[Dick Dastardly]

Got an 06 Vantage. Leant it to a mate and it has come back with a small issue. He swears he didn't press anything but the button/sign with P on it (next to the window heater button) has an orange light on it and now the parking sensors aren't beeping. Pressing the button does nothing - it won't move or take the light off. Any ideas?