Disco 4 (LR4) Radio, sat nav etc not working

So I was driving in the car one day and my radio just suddenly turned off and wouldn't come back on. Then a few days later the battery completely went flat. We changed the battery for a new one and the radio hasn't come on since. Literally nothing comes up on the screen! Any ideas what the issue is and how we can fix it? It's a 2011 model.
Thanks, Sophie

I know nothing of the Disco 4, but the first place I would be looking is for blown fuses. Your Owner's handbook should have full details of the fuses in the vehicle.

Read codes.
Try hard reset.

lynall said:

Read codes.
Try hard reset.

Click to expand...

How do I do a hard reset? Also the fuel gauge keeps going to two lines and saying it’s low on fuel when it’s not!??