digital back lit mileage counter blank ?

The digital mileage counter on car has now gone.
Its located directly above the clocks in which have replaced with those lockwood dials, all that connects the dash unit is a electrical block in which cant remove.
Replaced all engine and passenger fuses still nothing, its just orange its back lit no bulb.
Tried disconnecting battery still nothing.
Its being sold so it has to be fixed not sure how to do this is it an ECU issue??
The trip computer sits in center consule but this works fine.
Peugeot 206 1.4i 04 fever