The Baofeng UV-5R radio has a keypad lock function. If you press and hold the # key, the radio will say "lock", and the keypad will mostly be disabled. Mostly disabled, because the red CALL key will still turn the FM broadcast radio on and off, and PTT will still key up the radio, and MONI will still disable squelch. Press and hold the # key again to unlock.
How did I find this out? I was bicycling across the Diag and tried to tune in WCBN 88.3 FM, and found instead that my radio was just making a high pitched beep and not doing anything when I went to adjust the frequency. It took digging out the manual at home and looking around for a bit to find the magic lock / unlock sequence.
The sign that your keypad is locked is a little lock symbol just to the left of the battery status. This image (via Amazon) shows the screen with all LCD displays on.
Note that turning the radio on and off does not reset the keypad lock!
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