(Pt 1) Caddy Can't CRUISE? ('09 XLR Convertible: Adaptive Cruise Control)

Description: Owner just bought this 2009 Cadillac XLR Convertible a few months ago, and discovered that the Cruise Control doesn't work at all: neither Regular nor Adaptive.
Also, he says the little headrest "seat speakers" don't put out any sound.

A fancy aftermarket Radio Headunit was recently installed by the previous owner.
Would that have anything to do with the Cruise Control?

Let's to some research and see why the Cruise Control isn't engaging...
The owner is insistent that we make ALL THE FEATURES FUNCTIONAL...some parts may be required!

TOPDON Phoenix Plus:
https://www.amazon.com/dp/B091BQNR3S?linkCode=ssc&tag=onamzpineholl-20&creativeASIN=B091BQNR3S&asc_item-id=amzn1.ideas.NHZL00NIDEPF&ref_=aip_sf_list_spv_ofs_mixed_d_asin

TOPDON TORNADO 90000 BATTERY CHARGER:
https://www.amazon.com/dp/B09XV64Q49?linkCode=ssc&tag=onamzpineholl-20&creativeASIN=B09XV64Q49&asc_item-id=amzn1.ideas.UKPVIGM4POWZ&ref_=aip_sf_list_spv_ofs_mixed_d_asin

Enjoy!
Ivan Close description