It is not possible to adjust the screen brightness. However, you do have the ability to change the contrast of the text on the screen.
Find the Up Arrow, OK button, and Down arrow to the right of the LCD screen.
Press Down arrow until Contrast is displayed on the screen, then press OK.
Scroll using the arrow keys to increase or decrease the contrast setting (there are 11 different contract levels) and press OK to save the setting.
To return to the home screen, continuously press the Status button on the panel until the screen reverts to Disarmed.