So i bought this note 4 off ebay. My other note 4 is busted (screen popping out, turns on and off) and i didn't want all the stuff i had for it to go to waste, i have a newer S8 too but i need a spare phone.
And off the box it would not turn on! This was fine you know because i was used to my old note 4 needing to be perpetually charging to stay on. That's just how it is i guess.
But to my surprise the real issue came up.... It wouldn't recognise charging! I put its battery on my old phone it had like 78% charge and was able to charge. I tried my old battery on it and it also wouldn't charge or turn on. So... i took the phone to a shop and was turned away cause they gave up and the other offered to replace the charging port for $150AUD then $120AUD (seemed like a an obvious scam).
They were able to boot the phone! Just from messing around with the battery more. And it seems if the phone is able to boot it can charge. I also did rigorous tests at a local food court like fingerprint, nfc tap and pay and flash photography is fine. However.... even though it was plugged into a power bank and was at 70% battery the phone died... And guess what it wouldn't boot and it wouldn't charge again.
I took it home.... My friend lent me his note 4 on the way with a newer battery. Over the night i got down a method of mitigating the issue... It seems the phone has an inability to initiate the battery to charge when it dies. So the most reliable way to restart it is that you have even my busted Note 4 and you charge it for like 5 seconds then you plug that battery onto this note 4. I made an imgur post about it.
This makes sense of why the phone booted at the repair shops as i had initiated the phone on my old phone on the way back by chance. The weird screen also confuses me. Odin i recognise as custom rom thing perhaps it was previously rooted then improperly installed with stock samsung rom.