Carminat live Megane 2011 boot loop

Please help, I have tried everything! My Tomtom Carminat live seems to be stuck in a loop when I put the SD card in. I get the Renault images, the warning and then a screen which shows a map of my car in the water (I live near the coast!). It then just goes back to the timer and keeps rebooting. During the small amount of time I have, when the screen is on 'the water' I can access menus. I have been on Tom Tom home and updated but not bought any maps. I have reformatted the card (Fat32, slow format), popped it in the car to get the files and backed up. I have driven around for an hour in order to get a GPS fix but it just keeps rebooting.

Any suggestions would be really useful. I should warn you though that I've read a lot of stuff and don't understand it so please make sure your advice is written for a complete idiot!

Thanks

Carminat live Megane 2011 boot loop