Chosen Solution
Was given a MacBook Air (13-inch, Early 2015) 7,2 The screen will go blank, the keyboard backlighting stops. and the keyboard goes dead. If I delicately wiggle/flex the screen vs. the body, it will come back to life again. This sounds like the cable through the hinge is at fault. Is it replaceable? What part#, etc?
I bet you the issue is at the logic board displace connector. Corrosion on the solder joints is likely. I would inspect the area, post a pic so we can see things.
