Macs are generally machines that run smoothly. You will never really have trouble with the hardware unless you’ve dropped it from a great height, battered it, or spilled something on it. That said, if the fans on your Mac are suddenly running at full without any sign of slowing down or turning off, your MacBook’s battery isn’t detected, and the keyboard backlight won’t turn on, you have a slight hardware problem. The good news is, it is very likely an easy fix.
Fix fans running at full, no battery, and no keyboard backlight
This solution is for a MacBook or Mac that was otherwise running without any problems and suddenly began to exhibit this behavior. If you dropped your Mac, hit it or something fell on it, or you spilled something on it, and now have fans running at full, no battery, and no keyboard backlight, then this may or may not work.
You need to perform an SMC reset. An SMC or a System Management Controller manages various hardware and hardware controllers on your Mac. When there’s a problem with one, some, or all of them, resetting it is often the fix.
On a desktop Mac i.e., one that does not have a removable battery, shut it down. Once it’s shut down, remove the power cable and wait for 15 seconds. Plug it in again, and wait another 5 minutes. After that, press the power button to turn your Mac On. The problem with the fans should be fixed.
On a MacBook, the process is a bit different. Shut it down normally. Make sure the power adapter is connected. Hold down the Left Shift+Control+Option+Power button for fifteen seconds, and then release them all. Next, wait for five seconds and then tap the Power button. Your problems should be fixed.
If you have trouble turning the MacBook on, remove the power adapter and wait for 5 seconds. Next, connect it and at the same time, press and hold the power button for five seconds. Release it, wait 5 seconds. After that, tap the power button to turn the MacBook on.
If this doesn’t fix the problem with your hardware, you can try a PRAM reset but that doesn’t have anything to do with hardware or these sorts of problems. Still, it’s worth a try. If the problem doesn’t sort itself out, you should have someone take a look.
Ideally, you should take it to an Apple store but if you’re not under warranty, there are cheaper places to have it fixed.