The device was configured to listen to a SqueezeServer 7.6.1 and I left the device playing radio when I installed the SlimServer 6.5.4 when the radio stopped after the installation of the SlimServer.
The Squeezebox was now tuned off and since then I wasn't able to turn him on again. Unplugging the power-supply did not work, too.

What might be the cause that the device doesn't give any sign of activity (splash-screen,...) ? Any ideas what I can do ?