Delonghi Eco310 (Vintage Icona) water leakage inside

I have the Delonghi Eco310 (vingage Icona) Espresso Coffee Machine.

This morning I let it heat up as always, then pressed the button for coffee to fill up my cup. Pump worked, water boiled, pressure got the coffee out. Then all of a sudden, a popping noise inside as if a hose or tube came off and steam / pressure escaped with a “tfffffffffffff” sound. After that, no coffee came out anymore, the pump still worked, but all of a sudden there came out water from under the coffeemachine.

I turned it off, waited a bit for it to cool down and checked again, no water came out the normal way, also not over the steamer / frother on the side, but just lots of water from undernearth again.

I dismantled the machine to check all the hoses. Nothing slipped or popped out anywhere, everything seemed fine. I took out the little tube that goes from the top of the pump (anti drip valve) into the boiler. The O-Rings seemed fine, the tube had no damage or signs of leakage. Also the hoses coming from the watertank seemed fine. No visible damage. Pump seemed fine too.

I put everything back together, open this time. I let the machine heat the water up, my steam valve was open so lots of steam came out there at first - I closed it, but then it started steaming out of the anti drip valve? It seems the hot water is going back from the boiler into the top of the pump, rather than down into the coffee dispenser?

Does anyone have an idea which part could be affected? I am not sure if a new pump would fix the problem.

Thank you for your help