Diagnosis
The exit needle—the small one at the bottom of the pod holder—is almost certainly clogged. When coffee grounds and mineral scale mix, they create a paste that blocks the tiny hole.
How to Fix It
Unplug the machine. Remove the pod holder by pulling it straight up and out. Look at the bottom. You'll see a small, pointed needle. Take a paperclip, straighten it, and gently insert it up into that needle hole. Wiggle it slightly and pull it out. You'll likely see some black sludge. Then, hold the pod holder under warm running water to flush it out. Dry it thoroughly and snap it back in.
If That Didn't Work
The internal water line might have a more serious scale blockage. Follow the descaling procedure I mentioned for the grinding noise. If it's been months or you have hard water, it might take two descaling cycles back-to-back to clear the flow.
Heads Up
Be super gentle with that bottom needle. It's not meant to be scrubbed with a brush or bent. A simple poke with a paperclip is all the physical cleaning it should need.