I will check this out.Could be as simple as a loose fuse or connection in the back. Could be as bad as the head unit is gone.
Start simple. Check the fuse box for loose fuses. If that doesn't work, see if you can get behind the head unit and refasten each connection. Also look for loose wires coming out of the connectors, and any dark/burn marks on the connectors, especially on larger gauge wires.
It's a second hand, 8 year old car. I don't think there's any warranty here.If it is under warranty I would take it in and get it documented at the very least. I’m sure the head unit is pricey to replace.