Sleep button broken. How do I find out which part is affected? The sleep/power button of my iPhone 4 is broken; it suddently didn't really "click" anymore and just hardly reacted on my actions. For some hours by clicking really firm it still worked, but then the button refused to do any job.

I found out about a way to lock the phone via the touchpad, but when my battery is empty or the device switches off by any other reasons, I will not be able to switch it on anymore. So I did some research as I want to repair it on my own. I found out that the button itself can be affected (and replaced), and there is the holder for this button, which can also be affected.

How can I find out, which one of the two are broken - ideally without opening the device?
You will most likely need to open the device to tell this. I used to work at an Apple Store and am familiar with the design of the iPhone 4 internals. Good luck. iPhones are not fun to repair.

Also an iPhone with a broken power button will still turn on after the battery dies. Simply plug into a wall charger and allow the battery to charge enough, and it will power back on.