I would recommend turning the projector off at the mains to ensure that no power is going to the projector and leaving for 30 minutes.
If the LED sequence re-appears afterwards I would recommend contacting Promethean Technical Support directly and providing them your serial number.
Thanks, I’ve had it before with a different projector but the same model. It turned out the bulb wasnt sitting correctly – I wasnt sure if there was a special knack to installing the bulb? It’;s just i’ve tried loads now to no avail!