Water pressure low in boiler no hot water or heating

My boiler stopped working yesterday morning. Water was not getting hot. Checked boiler (ARISTON CLAS HE 24) says error with code 108 which means water pressure low request refilling. Water pressure is low reading at 0.4. Firstly I tried resetting and turning off and on the boiler, no luck, still get the error message. I have the filling loop already attached under the boiler. Tried turning the 2 black taps quarter turn, tried them on their own plus together plus one after another. No water is coming through the filling loop and pressure remains the same. I've also tried bleeding the radiators and then trying the handles under the boiler again. Still no luck! The boiler will not represurise. Anybody have any ideas what's wrong with it?

 

Under the boiler