06 TDV8 radio shows the Land Rover logo and the on off button is flashing but the radio will not switch on? Can switch on the FBH via the dash switch but the button did not illuminate?

battery?

More than likely your bluetooth module my friend... Water ingress? Check for wet in it, then check top left boot seal and see if its expanded and rippled on the corner

Mine went similar to this just before we discovered our battery wasn't up to scratch so replaced the battery. New battery = problem solved so perhaps yours is the same? 2011 4.4 TDV8 Autobiography

Check this -same issue. Check spare wheel well for water and the left hand side boot seal. Built badly but look good;

http://www.fullfatrr.com/forum/topic22942.html

So dry out the rear, check all connections for corrosion etc., try battery charge and battery disconnection procedure.... .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Water via tailgate seal, fixed, cured