Chosen Solution
My Macbook Pro won’t turn on since I tried to use a mini display to HDMI adapter. Now when I press the power button, I hear the hardisk and the sleeping light flashes one time, and if I wait 3 minutes, the screen is white for 10 seconds, and the Macbook reboot; When I close the Macbook powered up the sleeping light stays turned on. If someone can help me because I use this Macbook for my studies. Thank you!
Problem fixed! I pressed Cmd+option+P+R during 5 seconds at the boot, i heared the mac song and problem solved!
