you just have to wait for pressure to bleed out through grinds, leave group on until you finish drinking your coffee. My Gaggia Carezza is the same but by the time i have steamed the milk and finished drinking coffee, and I always purge steam tube until water flows also. It is then safe to remove. Wait at least 5 or 10 minutes.
The reason is these do not have a 3 way valve , but use a spring valve to block water coming to the group, pump pressure overcomes the spring and lets water flow to group, but also does not let pressure release, only way it can is via the grinds.
re the switch unplug it and physically try and un jam the switch. Coffee Parts* may sell spares or Di Bartoli Coffee Centre. or try Jaycar for equivelent if you cant fix.