2016 GMC Canyon #- Radio glitch

radio randomly comes on, without me turning it on. how can I
turn it on ONLY when I want it on

temp.xml (nhtsa.gov)
you should bring it to the dealer to have it looked at.

Obviously there’s some kind of short, whether a loose power wire, or some issue inside the radio.

I’d take it to a car stereo shop and let them have a look. You may luck out and it just be a loose wire behind the dash. If it’s something internal to the radio, well, a car stereo shop can help you with that as well.