Macbook Air keyboard/mouse not working

[mikeroq]

Boss took in a Macbook Air, I have very little experience working on any Mac hardware.

She thinks it's liquid damage from a few drops of water that may back worked down into the touchpad.

I noticed once Mac OSX boots the fan will rev up to what sounds like full speed.

I did a NVRAM reset, and that didn't change anything. I tried an SMC reset but when I hold the keys down after a few seconds it will turn on. From videos I watched and what I read it should not turn itself on, but after you hold the keys down, you have to hit the power button.

Keyboard and mouse seem to work outside of the OS. I booted verbose with Command V and that worked. Held down D got into the apple diagnostics ( which didn't seem to be working? ) but the mouse moved and keyboard responded. First it went black, then had a list of languages, I clicked on English and it put a checkmark, hit enter and it went past the language selection but just had a black screen with the restart and shutdown at the bottom. Didn't seem to do anything else.

At first I was thinking hardware issue, since I jumped right into opening it up and saw the keyboard runs through the touchpad, but I'm conflicted since the KB and mouse seem to work outside of OSX. The SMC reset not working, and the Apple diagnostic not acting right, and fan at full speed, makes me wonder if the logic board should just be replaced.

What do you guys think?

 

[Markverhyden]

Do you have OS X installed on another usb drive/stick? If you can power up with command + option to give you boot devices you will it as an option. But yes, sound like water damage but it's hard to tell if it's the logic board or top assembly.

 

[mikeroq]

I don't have anything OS X or any apple harware myself. Well except for my hackintosh at home.

 

[Markverhyden]

I always recommend to have a stick with OS X installed. Even if you do not have any Apple hardware you can use it to boot customers machines for diag's etc.

 

[Krynn72]

Yep, for macs its best to have a drive with OSX preinstalled, I have an SSD laying around just for this purpose.

That said, the fans revving up to full throttle, in my experience, means there's liquid damage on the motherboard. Can you see any corrosion anywhere? If you have to wait for a test OSX device, you may as well in the meantime pull out the logic board and look at the underside. Thats where the corrosion usually happens.

 

[mikeroq]

I never want to work on a Mac again.

Replaced motherboard, won't turn on. Light on adapter is off.

Got a second motherboard, this one works. But does same thing as the old one.

Replaced the touchpad, since the keyboard runs through it. Still same issue.

Replace keyboard???

Fan still revs up too.

I got the diagnostics to run on this replacement board says no issues.

Keyboard/mouse work "low level", like in Apple Diagnostics, or starting the internet recovery. Once in recovery, or in OS X they do not function. The power button works all the time.

I'm leaning towards this little board with the magsafe plug on it.

At this point I want to return all the parts and pull out of it.

 

[Ben Bessett]

I Would try running it with an external mouse and keyboard for testing as well. If you run into problems there, it's a logic board... otherwise it's the topcase assembly, in which case you need to replace that... it's a pain to replace but I have seen this method fix a supposedly dead machine (especially when the power button is one of the dead keys) a number of times now.
Good luck!

 

[mikeroq]

External KB/mouse work fine. Power button works fine.

 

[Markverhyden]

Personally I would have replaced the entire top assembly. But I know what you mean. All of these compact devices, Apple or otherwise, were not manufactured to be repaired for all intents and purposes.

 

[mikeroq]

Well I decided to order a KB off amazon, since I could get it in two days. Sadly it's for an 11" macbook air. Thought, well the layout and connector are the same, it's just slight smaller, maybe I can at least test with it. Plugged it in, no change.

I replaced that power i/o board. No change.

For shits and giggles, I unplugged the speakers, took out the air card, even took out the SSD no change.

Do I buy a whole top cover assembly with the KB and take the chance?

The screen? The fan? Burn the damn thing?

Did whatever is damaged, damage what i've replaced? Did I get bad parts?

 

[Krynn72]

When you test it, you've been putting that right angle flex cable between the dc-in board and the logic board on right? Because even if you have the dc in board plugged in with the four pin connector, it will still not power up unless you have that flex cable plugged in. Also its possible to plug it in the wrong way, so make sure you're not doing that, because that will prevent it from powering up also.

 

[mikeroq]

Powers on fine. Flex cable good. Have another update. On friday I tried that keyboard with no luck.

Today I tried the KB with the old touchpad and they both work. The new one turns out to be bad. It also fixed the fan speed issue too.

Ordered a top assembly. Sending the kb back and the touchpad. Might try the old motherboard. Might be able to return that too.