Remove the six Phillips screws securing the chrome rear panel to the Barista.

Once the chrome panel is gone, you get a pretty comprehensive look at what makes the Barista boil. Major components include:

A reciprocating pump.

A pressure release valve

A boiler (with an internal heating coil).

A steam valve which, as you guessed it, allows steam into the steam wand for making frothy milk.

A bird's nest of wiring supplying power to everything.

Remove all the Phillips screws holding the AC power cord and distribution block to the frame.