If you have a blinking blue light on your TV when you power your TV on it means that the power source is sending a signal to the internal parts in the TV to make the TV function. The light will usually blink 3 times then the picture will come on. This is normal.
If the blue light blinks more than 3 times before your picture comes on, or if the picture does not come on, this may be an indication that there is a failing internal part, and you may need to get your TV serviced. If you are doing a firmware update on your TV the light will flicker Red and Blue and this is also normal.