Assuming the pump is running (can you hear it?), there is the possibility of an air lock in the anti-calc filter in the tank, or it could be blocked. One would normally remove that before running the descaling solution and if you did that then there goes that hypothesis.
If you didnt take the filter out, perhaps try removing it then filling & refitting the tank before running the hot water for a minute or so to see if water is getting through the rest of the system. If it does then the anti calc filter is clogged or theres an air lock, either way an easy fix.
If it isnt that, then its likely either the pump or a blockage internally.