Chosen Solution
First let’s find out what you have. Please go here and enter the serial number from the back of your machine: https://everymac.com/ultimate-mac-lookup… Next I want you to hook it up to an external monitor and see if it generates a video output. UPDATE I changed the icon to your 2012 machine. Now there are probably two serial number printed on the RAM encasement. One should match the machines external serial number. The other is the # for the logic board. Does your’s match? Here’s how to remove the bottom cover: MacBook Air 13" Mid 2012 Lower Case Replacement Here’s a video on how to hook up an external display. https://www.youtube.com/watch?v=xg-APRYm…
Take the macbook to the nearest workshop and have a technician to take a look to your motherboard, it could be an electrical problem like a protection diode
