There are a few reasons why the light around the door release button blinks. 
Please adjust or check these options:

1.  The time and Date stamp is not set or has been lost due to power interruption

To set the time and sate stamp, open the panel on the bottom right portion of the monitor.
Press the second button named (CLOCK ADJ).  This should bring you into the clock adjustment mode on the video screen.  Press the (PLAY/ALTER) button until the desired date and time are set.  The format of the time and date stamp is as follows: "Year/Month/Day".  Press (MODE EXIT) to exit the clock adjustment mode.  If the button continues to blink, move on to step 2.

2.  There is a new picture(s) stored in the memory.

To retrieve the picture and stop the button from blinking, open the panel on the bottom right portion of the monitor.  Press the second button named (PLAY/ALTER) until all of the new pictures have been viewed.
The light should stop blinking once all of the new pictures have been viewed.  If the light continues to blink, move on to step 3.

3.  If there are magnetic sensors installed to the door status function, the door may be ajar.
The blinking button signifies that the sensors are not touching.  In order to remedy the situation, the door must be closed until the magnetic sensors are aligned.