An hour ago I closed the display my Macbook Pro. it goes into sleep mode. After dinner I returned, opened the display and wanted to continue with my work, but I recognized it was switched off completely.

I tried to press the power button and received nothing. I also noticed that the green light on the power supply plug which is plugged into my Macbook is off. Same thing with a power supply from the Mac of a friend of mine.

What could I try? Some suggestions? What could be the problem here??

I already tried using the battery to start, no success, also taking the battery out completely, no success. Even if I press the small button for showing the current battery charge, none of the leds starts. It's like the Mac is completely dead.