1980 C3 Corvette, radio and cigarette lighter won't work?

[TheBonecrusher89]

My friend has a 1980 C3 Corvette and he says that the radio and cigarette lighter used to work.
I've checked the fuses under the steering wheel and they're all fine. Also, the motorized antenna won't go back down now either.
I'm mechanically proficient, and I did a top-end performance swap for him earlier this year, but I have no idea where to begin looking for the culprit of this problem.
Thank you for the help!