Worcester Boiler, empty syphon blocked,

I should say that I did this whilst the blue and red lights were flashing - so I would suggest you do the same and wait till the green boiler light (the flame symbol (🔥) at top-left on the display cover) is OFF before removing the cap.
All the best to everyone out there!
Also thank you ‪@peterwang4307‬! I followed the instructions on you insightful Worcester boiler syphon video ( • Worcester boiler, syph... ) and it worked fantastically. I did this video to show the results. Over an hour later, everything on the boiler is still working brilliantly. Thanks again.
P.S: some people on Peter’s video commented that the procedure was unsafe and you needed a Corgi approved gas plumber to do this otherwise it was unsafe. IT IS NOT UNSAFE. There is no need to touch or go near the internal system or shut any gas off - it’s nothing more than taking a cap off a valve with a bucket under it.