The first thing to check is the seating of your water tank. Just a few grains of coffee grounds or dirt underneath the tank are enough to break the watertight seal. Make sure the area under the tank is absolutely clean.
That's always worked for me when I've had the leaking problem.
Rinsing cycle at start up is electronically programmed function. Unplugging is a temporary solution.
Jura will not sell parts or offer any guidance.
I could look into more details to find an answer but the model Capressa 50 is not listed in my Data base. Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/edward_bbd2c7ff4ee1828a
