Chosen Solution
I tried every keyboard combination but it didn’t turned on. The fan is working but it doesn’t light up the Mac logo or the keyboard. interestingly if I connect a phone it charges. I tried to disconnect the battery, the SSD and the LCD. But it didn’t worked.
Give this a shot. Disconnect the battery and Mag-safe adopter. Press and hold the power on button for ten seconds. Reconnect the battery and then the mag-safe. This should give you a spontaneous reboot. If not go to @danj answer.
OK, not good ;-{ Your logic board will need repairs or you can just replace it! MacBook Air 13" (Early 2015) 1.6 GHz Logic BoardMacBook Air 13" (Early 2015) 2.2 GHz Logic Board Here’s the guide: MacBook Air 13" Early 2015 Logic Board Replacement