Vaillant Turbomax VUW 242/282 not firing after draining

Hi hoping someone can help, I have the Vaillant Turbomax VUW 242/282 combi boiler. I had to remove 2 radiators for decorating, I turned the mains water off, drained the system from a downstairs radiator, (without turning boiler off! It was in taps only not CH) removed the two radiators, capped off the valves, turned mains water back on. Little while later I noticed we had no hot water on investigating I relised I didn't fill the boiler back up so I opend the filler tap and filled to 1.5 bar. As it started to fill I noticed the temp gauge needle went from 0 degrees right up around the scale to max and then back down to 0 degrees again... Not sure if this was normal or not?

I bled the rads, and checked the air vent valve in the boiler was loose and also bled this to make sure no air, I bled the pump and this was also ok.

I trying the hot tap the boiler doesn't even attempt to fire, the lights on the front panel don't change other than the tap indicator light. The micro switch operates ok aswell. On trying the CH same thing happens, radiator light comes on but boiler doesn't even attempt to fire.

I checked the temp override button and this appears ok, I tried pressing it several times and it doesn't move so I presume it's ok.

So Im not sure if having the rads off the system is causing the problem, or if I got a big air lock? Or if I've broke something..... Any ideas would be grately appreciated as got no heating or hot water at the moment... And it's tad nippy.

Thanks

It is a little foolish to drain the water from the boiler while leaving the mains connected to it.

Sound to me as if it will have overheated.

Tony

Stevo, safe to say you might need services of a Heating engineer who is familiar with this boiler. May I suggest you stop worrying as what is done is done and cannot be undone now (without help of a friendly knowledgeable heating engineer)

A good chance boiler fired and shut down due to lack of circulation as pressure was at zero. Heat in the heat exchanger spiked the temprature gauge, but unlikely you have killed the boiler. It might be prudent to get the boiler serviced as your boiler has a flow sensor that should not allow the burner to fire if pressure at zero.

As said earlier, you need someone who knows boilers, not someone who pokes and hopes to clear a fault