Kristijan wrote:Can i do this by just running water through the screen?

image

Тhis is what came out from the screen after running some water

You're overthinking it. With a shot timer of only 23 seconds, there is no chance you hurt anything. Dial it in correctly with more coffee and enjoy (you're going to need a grinder for this, as it sounds like the cafe's grind setting was too fine). You could certainly take it apart to clean if you want, but not necessary. You will eventually want to get some Cafiza and backflush on a schedule for routine maintenance.