Audi Repair: Possesed A8L, vagcom, ground connections

Question
Hi there, I'm one if the Audi Experts on this site and am having issues with a 2003 A8L with a 4.2 (BFM) engine.

It all started with the battery giving up which was then replaced but came up with another problem with the key,

when the key is inserted into the ignition nothing happens, ( usually the steering lock releases) and when it is turned again nothing!!!

when the start button (next to the gear lever) is used it works intermittenly and when the car is running the driver display shows a red signal with a key hole on top and a key below it.

i have carried out diagnosis (using VAGCOM) and can send you  the report if required. will replacing the ignition switch rectify the problem or do I have to replace the starter button with the control unit and if so what do I need to re-program the new control unit. any help will be appriciated

Answer
From your question, there is obviously a problem with the key being recognised.  So maybe the key module is not getting power?  I would check fuses and relays, and look in the manual where the key circuit power comes from, check that you have good power there.  Also check that the ground connections to it are solid.  Intermittent problems usually mean loose connections, not failed components.  It may also be a control module problem, but again check the connections first.  I do not have the wiring diagram for that car, but would imagine there is a start control unit which is relying on a few inputs before it will allow engine start, such as key in ignition, trans in N or P, etc.  Make sure all the check signals are there, esepcially the 'key present' signal.  Let me know,  Jan