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What boiler is it please.
If the boiler is pressurised what pressure have you set it at, it needs to be about 1bar to make sure it will work
It seems that the boiler is full of air. You can try turning the temperature on the boiler down as low as you can turn the system on and turn the pump up to speed 3 then keep switching it on and off every 30 seconds or so to try and push through the air lock