Here’s how to access the self diagnostic / configuration menu on a Nissan Almera 2003 SVE (N16):

1. Start the engine
2. Turn the radio on
3. Turn the radio off
4. Hold the info button in then:
5. Turn the volume knob up (clockwise) until:
6. Diagnostic menu appears

From here you can do various things: run self-diagnostics; reset/change the main service counter; various other tests for the climate control, sat nav system, etc.