Glow worm 38 cxi combination boiler?

Have just moved into a new house with a Glow worm 38cxi combination boiler fitted.
Decided to decorate so took small rad off to paint behind.
Switched both ends of rad off and removed it.
Re fixed rad and opened one valve and bled rad, when bled opened the other end of rad.
Now boiler will not come on, red light flashing and nos 04 showing, any ideas?