I used to have one before I gave it to a friend and bought a VBM piccolo :)
I had mine for 3 years and didnt remove the shower screen very often, well ok, hardly at all, I did flush the machine after each use, anyway the coffee residue had built up in the screen to the stage water was barely getting through, the gasket was stuffed as well, see here for an example
scroll down to my post about the filter baskets, bad doesnt cover it.
the shower screen does come out and you more than likely need to replace the gasket, about $20 from breville service.
I would not have taken the thermobloc apart, but when you see all those screws the temptation is sometimes too great to take it apart isnt it?, when you put it back together, make sure you torque those screws down tight, last thing you want is water leakage around the thermobloc.
anyway dont really like the look of the inside of the thermoblock, cannot see how but it looks like the coffee has been backing up through it or it needs a serious descale.
the circuit board behind the switches?, umm there is isnt really that much behind those switches, 2 microswitches and 3 press buttons, the main controller board is down the rightside leg.
seeing the machine hasnt been cleaned properly in the 4 years, I am wondering if it is clogged up with coffee grounds and the water cannot flow through and a safety cutout has activated.