Chosen Solution
My macbook air isn’t powering on but when I plug in the magsafe charger, it turns orange. An SMC reset (Shift-Control-Option keys and power button while plugged in) makes the light turn green briefly but it still won’t power on and the light turns back to orange within a few seconds. Also with the back panel taken off, I can hear faint clicking noises, but I don’t know where its coming from
The magsafe leds behavior is the correct one for Smc reset. A light clicking sound instead is pretty bad news, that’s usually caused by a faulty mosfet and indicates a logic board failure that would require a component level repair or a more reasonable replacement. Being a pretty old board may come cheaper than a repair if you DIY.