Having taken apart 2 touch pro's several times to fix dead keyboards I thought I'd take pics. This is not what I'd necessarily recommend doing as it could indeed void your warranty but if like me, you're tired of exchanging your phone, go for it.
Just don't blame me if you break it in the process.
Photo 1: Back cover and battery removed. The 4 screws are tiny torx T6 size. I picked up a handy little blue torx driver with 10 or 12 different sizes for $6 at Lowes.
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Photo 2: Here's the 4 screws removed. Total excitement.
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Step 3: Once the screws are out, if you press from inside the battery area you can push the keyboard up a bit on the corner. From there, slide a finger nail or knife along the gap and the keyboard will pop loose. Takes a bit of wiggling to get the back side off.
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Step 4: Again, takes a bit of wiggling to get it all the way off. When you do, the cable towards the back may come loose but its easy to reattach and is circled in later pics.
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Step 5: Here's the 3 trouble makers circled in red. The one in the center I've plastered with electrical tape to keep it attached since its popped off 3 times.
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Extra pic 1: Here's the pieces detached so you can see.
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Extra pic 2: Here's a possible reason why the middle one comes off so often. If you press against the inside where the battery goes it pushes against the ribbon cable that pops off so often. (edit: its sad that the little kid inside this 37 year old body says "haha, it looks like a penis" every time I see this pic.)
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Hope you enjoyed my boredom and maybe it'll illuminate a tiny bit why the keyboards have issues. I'll try to answer any questions you still have after this. Above all... try this at YOUR OWN RISK.