storage full and the phone went off

Do this If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support

This is apple bug looks like. The phone do nothave boot up memory reserve for operating system. IF your storage is full and device is shutdown it wont restart at all. It go to frozen mode. I faced this issue with IPHONE 7 + and its not starting at all. In order to check , i recreated the same scenario with iphone 6 and its same. Its bug from apple.

I checked with Apple service support but they are not accepting it and saying that its hardware issue which is not true. If it is hardware issue it wont happen with multiple device with same test scenario. I am software professional and i did my RND with all.

I would request take this as challenge and fix the bug. your technical support team charging $500 which i can buy new device, which is totally wrong . If your device suddenly shutdown when memory is full it wont restart. This is bug from apple.