I would call the dealership and have them help you so you'll have peace of mind.
Did you just replace or have had you car battery disconnected? I had an A3 that did the same thing and needed to be synced to the car again. There are instructions on how to do that online. I do t k ow if it's the same situation as your but that fixed my issue. Hope this helps.
Key fob will need to be reprogrammed. To do so, call Audi service and set up an appointment to get it looked at. Shouldnt be too long of a service. Expect an hour or less
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