Guide Sat Nav

please help my guide 3000 Sat Nav does not work?
when you turn the blue lights come gift anything on the screen and then there is no manual reset button
This can have a reset button somewhere that is often a small hole in a small button easily accessible with a straightened paper clip or similar. one have a look and give a press while blue light is on – just hold the button in seconds. Sorry if it has one – the 3 different they all do I have
Sat Nav – beginners guide