GWTN156-4 keyboard issues,The built-in keyboards couldn't even work while on the BIOS screens

PWeasel

Hi there,
my office bought a couple years ago a batch of GWTN156-4 laptops, they worked GREAT till a couple months ago, when 3 started to have issues. started as keyboard non responsive at first, forcing us to use USB keyboards.

The built-in keyboards couldn't even work while on the BIOS screens. Then the problem evolved to the point that one started shutting itself down a couple seconds after booting, and another just turns itself on as soon as I plug it into mains, then it shuts itself off during or right after booting up to then ignore the power button when pressed unless I re-plug it back to mains.

At first I thought it was a windows update gone wrong, but the fact that not even while on the BIOS screen the built-in keyboard was unresponsive eliminated that possibility.
All the laptops are in good care, never spilt any beverages on top/[Sensitive Content] nor they were dropped.

Has anyone experienced anything similar with this model?

[Edited the thread to hide sensitive content]

billsey

Unfortunately those models are specials only sold through Walmart, and a portion of the deal Walmart negotiated was to provide all support for them, so we don't have access to any technical documents through Acer. You are right in that it can't be a Windows update issue, though there was a recent update that did affect USB ports on some models, and the keyboard connection is likely done through an internal USB port. Is the power button integrated into the keyboard on those? If so I'd start looking at that as a potential avenue to the symptoms.

PWeasel

yup. the power button is integrated into the keyboard. there is no separate ribbon cable for it.

billsey

OK, it could have gunk under the button that causes it to not fully depress easily or it sticks when pressed. Less likely is an issue with the membranes that form the basis of the keyboard matrix, where when you press a key two or more layers of the membranes connect through traces integrated in the surface of the membrane. If there's been a liquid spill that affected those layers you can get intermittent contact or constant contact, depending on whether the contaminant is conductive or not.

I'm guessing the most likely scene has the power keys stuck, causing them to always look like they are pressed…

PWeasel

https://community.acer.com/en/discussion/comment/1304004#Comment_1304004

problem with that is that the keyboard is plastic-riveted to the upper shell and the whole keyboard assembly is sealed

billsey

The is why the potential issue with membranes is so much less likely to be the case. The key caps themselves are removable, though not easily, and stuff can get under them.