The LED light on your BlackBerry phone gives you a visual reminder of your BlackBerry's status. If your BlackBerry phone is working properly, a flashing red light means that you have received a new message. However, if your BlackBerry phone's screen is dark and you also get a flashing red light, it can mean that your BlackBerry is having a power management problem. To stop the broken boot cycle and end the flashing red light, you need to do a battery pull.
Turn your BlackBerry phone over and remove the back cover. Remove the BlackBerry battery for one minute.
Hold the red "End" button down as you replace the battery. The red LED light will stop blinking and stay on.
Hold down the green "Call" button for a moment and then hold down the red "End" button. Alternate pressing these two buttons until you see the hourglass icon on the screen of your BlackBerry. Stop alternating between the buttons and wait for your BlackBerry phone to finish booting up.