Keyboard unresponsive on start, solves by tapping bottom of computer

Hi!

I followed your advice @zpl and cleaned and reconnected the two cables (the keyboard cable was difficult to get back in place but it worked after a while).

After a first start up the keyboard and trackpad worked directly, which happens from time to time normally as well, so I will now do some restarts during the day and see if the problem comes back.

I'll keep you updated!

Hi again,

It first seemed like disconnecting and cleaning the cables solved the issue, it worked for ~20 restarts during a day.

But then the problem came back and tapping on the bottom of the computer didn't work this time.

Now this leads me to another suspicion, that it starts to work again if I open the bottom enclosure and disconnect and reconnect the battery cable from the large PCB it's connected to.

Could this mean that a new battery replacement would be a good idea? After all the last time I swapped the battery was 5 years ago.

That's possible! You could also try removing the battery for a while and just using the computer with the charger connected for a few days to see if the issue persists without a battery connected.

Hi again,

I disconnected the battery and removed it from the laptop, running only on an original Apple charger for a few days.

Unfortunately the problem kept coming back, so I guess this removes a potential bad battery from the equation.

So, I still get an unresponsive keyboard and trackpad at start-up sometimes, and what seems to solve it is to tap hard on the bottom of the laptop.

Any other ideas what I could try out?

Thanks for the help so far!

Hi,

I downloaded the Coconut app as you suggested @danj and I'm attaching a screenshot of the main window of the app. I switched the battery in 2019 following the guide here on ifixit and it seems like the app is saying that the battery is in good quality.

@malmoola - Good! Most of the time it's the battery being worn out. Still keep an eye on it.

Did your system suffer from a spill? As that would aim us to the keyboard with a stuck switch or as @zpl pointed out a dirty/loose cable connection.

Hi Dan!

So far no spills on this one, but I'm re-thinking my hypothesis, that disconnecting and reconnecting the battery from the large PCB solves the issue.

So maybe it's a bad battery again after all?

Hi again,

I disconnected the battery and removed it from the laptop, running only on an original Apple charger for a few days.

Unfortunately the problem kept coming back, so I guess this removes a potential bad battery from the equation.

So, I still get an unresponsive keyboard and trackpad at start-up sometimes, and what seems to solve it is to tap hard on the bottom of the laptop, or press on it.

Any other ideas what I could try out?

Thanks for the help so far!

@malmoola - Just noted the CoconutBattery snap, this systems battery was replaced in 2019 so it’s not the original one and looks like it’s in reasonably good health.

Are you sure the ribbon connections are sound? Is the cable damaged are the contacts properly secured and not damaged? The ZIF connectors have a latch which folds up and down are the in the correct position?

Sounds reasonable.

But what intrigues me is that I never have a keyboard problem when the computer is running.

It’s only a problem during start-up. So I guess the system is waiting for some sort of response from the keyboard during start-up that it doesn’t get due to some hardware problem as you say.

@malmoola - Batteries swell up which can press against the cables which pass over it. Just making sure the batteries health wasn’t the issue.