Is it wired to dim to match the dashboard lighting? Most vehicles dim the radio when the headlights are on and it is set by the dashboard light level.
Have you tried to increase the dash lighting?
Also, there may be a lighting setting in the radio menu.
Living in the gnat capital of the world, Tifton, GA
2016 JayFlight SX 212QBW
Amateur Operator N9XGZ D*Star
2016 F-150 Lariat SCREW, 5.0L, tow package, Softopper