Honeywell makes programmable thermostats that centralize operation of your home's heating and cooling system, helping you regulate the indoor temperature, humidity and air quality. Your screen may become locked, meaning that you can't use touch-screen buttons. There's an additional security setting where the screen is only partially locked, giving you access to only certain buttons. Removing either screen lock should only take seconds.
Unlock a partially locked screen by pressing any locked key, which will bring up the "Screen Locked" message. Next press an unlocked key, which will likely be the temperature up and down arrow keys. This will unlock the screen.
Press the "System" key from the home screen. Five blank touch keys, flanked by the "Done" and "Cancel" keys, will appear. Hold down the middle key for about five seconds. The Advanced Settings menu should come up.
Change the User Setup Number, found in the bottom left of the screen, by pressing the middle arrow keys up or down. Set the number to "0670," the universal unlock code.
Turn to the arrow keys on the right side of the screen. Press the keys up or down to change your options. Selecting the number "0" will unlock the screen, while choosing "1" will partially lock it. You can fully lock your screen again by selecting "2."