How can I repressurize my Worcester Bosch 350 combi boiler system?

Please can you help me? I have taken off a radeator and put it back on and bled it. But have losed the pressure on my Worcesrer 350 Bosch combi boiler. I have put water back into the boiler with a tap on the loop but the boiler just has the red light on and the boiler and the programer are not working.Hope you can help me to repressurize the system.?