car will not start and power top will not operate on 2003 BMW Z4

my 2003 bmw z4 will not start and the power roof will not operate.
Day one car started but battery performed progressively more sluggish with each start.
Day two the engine would not even click when attempting to start it and the power roof will not operate
Have replaced the battery, made no difference.
All other accessories and dash illuminations are working.

Asked by for the 2003 BMW Z4
it sure sounds like you have a poor connection at the battery terminals. you will need to have this checked at a BMW specialty shop. they will have the correct software to diagnose this problem.