phone turns off after apple appears for 15 seconds
after replacing the toggle switch/mute switch, the phone would no longer power up or respond to any button pushing.
i tried soft reset, hard reset, dfu, plugging it into the computer, letting it charge... everything. the phone is still an expensive paperweight.
the only response i can get from my phone is when plugged into a wall outlet. when i press the power button, the apple appears for about 15 seconds and then goes black. after going black, you can see where the screen appears to be on for just another second or two (like a screen burn on old tvs) and then it goes completely black (like the phone is off)
With my iPod, this is a symptom of a severely discharged battery. My son occasionally runs it down, then puts it on a shelf for a few weeks. It cycles as you described about 5 to 15 times when first plugged into the computer. I assume each cycle injects a little charge in the battery, which eventually recovers enough to allow it to boot.