How do I retrieve this for the TLX? Our 2011 had the code on a plastic card which came with the MDX, there was not one or we never received one with the TLX. Emailed salesman and he said I could find it by the battery, didn’t see anything there.

I found this in the FAQs in the online owners manual:

Q: After my battery was disconnected or went dead, the audio system is asking for a code. Where do I find this?

A: In most cases, you do not need to enter a code. Turn on the vehicle and the audio system, and press and hold the power button until the system reactivates.