Update FWIW. I sent my TK-880 back to www.used-radios.com to verify firmware and install the correct V2. Turnaround was 7 days total. I got a call from the service manager and he got the tech to work it over and correct it. Fired it up this afternoon and all seems well, buttons are correct for me, groups and channel programming are right, and there's no 'yyyyyyy' across the display. Hopefully, it won't revert (it didn't do it the first time until power had been cycled multiple times). They suspected corruption in the software/firmware or such. I would likely mention here if I'd received poor or sub-par service from a vendor, so it's only fitting that I complement one with great service. Some might say I paid a premium for a used radio but part of my rationale was the 90-day warranty they provide, and that it came complete with mic, power cable, and mounting bracket. Now I can add good service to that. And thanks to all of you who helped diagnose the issue.