Chosen Solution
So my note 4 won’t turn on at all and when I tried changing it with the power off, the battery symbol just keep flashing on and off. I have tried pressing the volume key + power + home button but it didn’t work at all. And before this happen, my phone kind of started to lag and the battery started to drain drastically before turning off by itself and restarting the phone and then turn off again and now it won’t even turn on.
It sounds like your battery has failed. Some phones need the battery to have a slight charge to turn on. I would try replacing the battery. Theres a pretty good chance that will fix it.
