It will require an “ALLEN” key which you don’t have. Call a friendly DIY man with a set of keys, and slacken the one on the oil pump at the same time as pressing the red button on the control box, the oil will squirt out as foam, the boiler will splutter and go on as you close the key, better still , get the service engineer to fit a 2 pipe system ( TIGER-LOOP ) it will NEVER happen again. Total cost about £ 85 well worth it.
Camray 5 Boiler
Yes you can bleed radiators with a combi boiler, but remember to check the pressure gauge on the boiler, if the pressure drops below 1bar the heating will not work, and with some combi’s the hot water will not work also. All you have to do is once you have bled the rad is to check the pressure gauge and top up the water if it goes below 1bar by opening the valve’s on the filling loop that goes between the mains feed to the boiler and one of the central heating pipes ( these are normally found on the pipe work just under the boiler). But don’t go above 1.5 bars.