It used to not be like this, back when I had an iPhone 4 it would boot immediately. But then it would die as soon as it got to the locksreen, halfway through me

It used to not be like this, back when I had an iPhone 4 it would boot immediately. But then it would die as soon as it got to the locksreen, halfway through me putting my passcode in, or as soon as I unlocked the phone. Having to wait a little bit tops the frustration from getting your routine interrupted by the phone dying at random points. I usually waited a few minutes anyways to avoid the random shutdowns.