Fun with iPhone 4 Button Replacements
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The third adventure into the bowels of this phone was for very good reason: Both the home and lock buttons were barely working. The first one that went was the lock button, and this happened months ago. One day it decided that it was no longer interested in clicking, barely moved, and was clearly sitting lower in its socket. Given enough force, it would do its duty, but I had to press extremely hard. Asking the Google machine what to do, I didn't find a single reasonable answer for a fix besides walking into an Apple store with puppy-dog eyes hoping for an exchange for a refurb. I rummaged around iFixit's teardowns and finally decided that I'd order a replacement button. That didn't go so well, as explained here in detail, since this part is actually just the cover of the actual button. The next logical part to replace was the cable assembly and contact that interface with this button cover, which I describe below. I also ordered a new home button assembly. When the parts arrived it was time to completely tear down the device, and according to the picture below, also do some heavy drinking?
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What they don't tell you in the how-to's and teardowns, is that you're going to lose these dozens of tiny screws that hold all these components together, get them all mixed up, accidentally inhale them, etc. Solution: Line up a bunch of shot glasses, as shown above. Each set of screws goes in a shot glass, and line them up in the order that they came out in. This makes putting the phone back together much easier and with much lower risk of losing something. And in the event things go terribly wrong, you can drown your sorrows in some top shelf booze; you're already set up for it.
Once I had everything apart and reviewed the teardowns online again, it was very clear that the issue was the little button hidden underneath the metal button cover. It lives on a small, funny looking flex board along with the proximity sensor, ambient light sensor, and noise cancelling mic. The lock button section wraps around a metal bracket that screws to the top of the case, butting up against the metal button cover. The replacement part comes with a mild adhesive already applied and protected by peel-away pink plastic sheets. iFixit has fantastic step-by step tutorials on how to pull this thing apart; if it's your first time, definitely check this out.
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The image above shows the replacement flex assembly (right) next to the freshly removed faulty one (left). Unfortunately, the foam ring on the original flex is where the earpiece speaker sits and it gets completely destroyed when you remove the speaker. The remnants are also nearly impossible to peel off intact, so the earpiece speaker will no longer be sitting on anything unless you fashion a replacement out of some similar material. The same is true for the black plastic piece right above this foam ring in the photo, still stuck to the flex. It covers a few resistors and a cap behind the sensors, but I didn't have any adhesive on hand to attach it to the replacement. Had I done a thorough job instead of half-assing it, I would have transferred this piece over to the new part.
Moving on, the replacement of the flex assembly went quickly once the phone was disassembled. Everything tucked into its correct spot rather easily, and the adhesive that was already applied to it helped quite a bit with keeping it in its place. I've never been more excited to click a button. Once the bracket that holds it in place was fastened to the case, I pressed and released to the beautiful, almost sexy, tune of a button click. Works like a charm now - just like new.
Now on to the home button...
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There are two problems with my home button: It takes significant force to get it to register a click, and when it registers, sometimes it registers multiple clicks. This can get really irritating, and makes flipping between apps (a double click) difficult. Luckily, the entire button assembly is just one part. Unluckily, you need to take the display off of the phone, which requires the most extensive teardown.
To replace the home button, you have to go a step further and pop the screen off (reference). The home button has a metal dome underneath it that does the clicking and the entire assembly sits on a circular metal disc. A little flex connector sneaks out from underneath, passes through a hole in the front of the phone, and locks into a very tiny connector on the back side. I tested the new button out a few times before putting it in, and it seemed to be clicking fine. However, when I was ready to put it in, it no longer clicked. Womp womp, must have been defective. The original button still had some clickeyness to it, so I put it back in after cleaning off the contacts with a little alcohol. After reassembling the phone, I found the issue to persist, so cleaning the contacts may not have helped. It's also possible that the metal disc under the home button isn't an electrical contact. This is likely since the metal disc clicks as part of the button appears to be covered with a thin layer of plastic. I should have checked if it was indeed exposed metal with a multimeter; this button could be completely self contained. I suppose I'll know once I have another go at replacing it with a new button.
The next day I got an email from iFixit checking to see if I was happy with my order. I explained what went down with the replacement home button and they immediately shipped me out a replacement at no charge. Fantastic service, I'm very impressed. I've yet to have another go at it, but will soon enough.
I also noticed this:
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The moisture indicator right behind the docking connector, well, indicated moisture. At some point some liquid got in that connector, and that's never good. It very well could be why this button failed if it got all the way into the tiny home button connector nearby.
Even though I still have this issue with the home button, it's fantastic to have a working lock button again. It's taken a few days to get used to not smashing it down to get it to work, but I'm learning, slowly.
