Arduino Mega Green power LED is on but the pin 13 LED is not flashing

Hi Guys,

I have a quite big problem which makes me crazy. I have a mega board. when upload a sketch in it,

led flashes (i think) two times, then sketch starts running and pin 13 led starts blinking. this is

normal as i know from my uno.

The strange thing is, when i unplug or reset it, again power led is on, first pin 13 led flashes two

times, but no flash after. To make it work, i need to re-upload the code in it. I have a glcd display

connected to it which displays angle values from mpu sensor. I see nothing on screen when pin 13 led

is not flashing.

What could the problem be? I am completely lost.

Any help would be appreciated.

Many thanks in advance.