Not enough information. You mention programming. Are you using ProntoScript and do you have script in your home page?

Section 13.3 of the Dev Guide has this:

Infinite scripts

It is possible to create a script that takes a long time to execute and effectively blocks the control panel. In order to enable the user to fix this situation, a key combination can be pressed during the start-up of the control panel that disables the script engine.

The key combination to be used is: Backlight+Menu+ChannelUp. On TSW9500 devices, the combination to be used is Firmkey 1+Firmkey 2+Firmkey 3.

It must be pressed continuously during the start-up animation and the please wait screen. A diagnostic message will be logged to indicate the limited functionality available. The user can then use the normal download procedure to download a corrected configuration file into the control panel. Another reboot is required to start the script engine again.