Fixing "THEFT LOCKED" on 2021 GMC Yukon After Radio Replacement

Recently, I faced a frustrating issue: after replacing the radio in my 2021 GMC Yukon with a used one bought from eBay, the message "THEFT LOCKED" appeared, making the radio unusable. I turned to the dealer software SPS2 and the VXDIAG VCX NANO for GM scanner to reprogram it. During the process, the software asked me to insert a USB into my computer, which I did. After transferring the updated data, the system indicated I could safely remove the USB, suggesting the programming was complete.

However, when I plugged the USB into the vehicle's USB port beneath the climate control systems, there was no response, and it still showed "theft locked," with no software loading. After some trial and error, I used the Techline Connect diagnostic tool to remove the "theft lock." The next puzzle was how to update the software—though the files were on the USB, the vehicle didn’t react when I plugged it in.

I noticed that the USB port was a bit dirty, so I cleaned it, and immediately the vehicle recognized the update and began the installation process, which took about 30 minutes. From my experience, if you encounter similar issues, always check the cleanliness of the ports; details really matter!