Problem you have now it what to break.. you cant grip the heads of the bolts obviously so something has to give.. suppose if you could you might be able to pull upwards and the inserts would pull free and allow you to lift the cover but there again it would probably damage the plastic housings where the inserts sit and you then wouldn't be able fit the cover back.. would welcome suggestions from other members at this stage who might have other suggestions on how to retrieve these bolts with minimum damage..