Hi I have replaced the battery (definitely duff) on my KA but still start. Symptom are as if battery flat, no solenoid click/mileage read out goes off when key turned - but when i connect charger it says fully charged on a new battery? 

sounds like starter motor failed.

what was happening before battery change  (what was the symptons)

it may also be altinator fail.

if your in the aa etc get them out to check it

battery terminals on the cables in good condition? bolted up tight?  connections at other ends of the cables good?   it sound like the kind of problem caused by poor connections. But it could be other things

a dudd alternator won't stop the car from starting if the battery has been fully charged off the car.

if you switch the headlights on full/main beam and put the heated rear window on and the heater fan on full and the indicators does everything work with the headlamps staying on bright? and the dash lamps (oil etc) staying on?   

If not, then there is a problem with battery connections (assuming the battery is still fully charged)