Sounds like something is blocking the hot water pipe, either in the boiler or in the pipe itself. As suggested by another member, have you tried unscrewing the hot water head to see if anything come out ? If your steam tap is still working I guess you could always empty via that by tipping the machine over onto its side. If it was me I would probably think of unscrewing the boiler fill probe fitting on the to of the boiler and syphoning out the water. With the probe removed you might be able to get a small webcam or snake camera (or maybe a small dental mirror) to see if you can see if anything is blocking the water pipe hole. To be honest I'm not sure I'd even worry that much that the hot water tap doesn't work, I can't remember the last time I used it anyway. The water it delivers isn't really suitable for tea or Americanos anyway as its been boiled and superheated that many times it has a funny taste. I've really only ever used it for wetting a rag to wipe the steam wand clean.