If you are running version 27 of the firmware (or above) then See.Sense ICON has built in self testing functionality.
To access the self test perform the following steps:
(1) connect ICON to a powered USB lead
(2) press and hold the main button, disconnect the USB
(3) when you see a green LED indicator, release the main button - if you wait too long, you'll see a constant blue LED, if this happens, please try again
(4) on releasing the button, ICON will perform various self checks. During this time, it will illuminate the main and indicator LEDs alternately.
(5) Observe the LEDs. If ICON settles on any single LED for more than 5 seconds, this indicates a potential problem area - please note the colour of that LED. If no LED is illuminated for an extended period, no error has been found.
Do let us know how you get on.