Note 5 No Power, Won't Boot, Won't Charge

I have a note 5 that has never been water damaged and never seen any condensation at all, I have only used the original power adapter and USB cable that came with the phone, and a few days ago the Note 5 died and would not turn back on. Left it on the charger for a while and still would not give any indication of charging or any signs of life at all. I have repaired countless Note 5's and never seen this before so I decided to take it apart. Used a volt meter to check the voltage of the battery which read 2.87 Volts, which is dangerously low. Next I checked to see that the phone is dispersing power correctly by checking the positive and negative battery terminals on the motherboard while I had the phone plugged in, and it read 4.24 Volts, which is good since phone batteries need 4-5 volts to charge, so the problem does not appear to be the dock connector and doesn's seem to be the motherboard, but I have already tried replacing the battery with ones that work in every other Note 5 that I have.

I also cannot boot into recovery or download mode.

There is zero physical damage, no dents or cracks and the AMOLED is in perfect shape.

Cannot even get the notification light to turn on under any circumstance.

Any suggestions?