Delonghi Caffe Corso Flashing Water Tank Error

Hello, my Caffe Corso worked fine until a few weeks ago when it stopped making coffee. I took the entire thing apart water pipes, pump, valve etc. and found the primary issue - a huge rock of limescale clogging one of the smaller pipes - and removed it. Water now flows, however, only for circa 10 seconds and suddenly it cuts out with the water tank light flashing. I can try again and it will work but again, only for circa 10 seconds. Does anyone have any ideas aside from the usual one of turning the steam nob because this only works for 10 seconds too. For the same reason, it cannot be properly descaled, although I've manually ran this. Thanks!