Of those dozens of chargers and cables, were any of them rated at higher than .5A? Remember that a cheap cable will limit how much current can be drawn even from a good charger. I'd say find a brand name (Samsung for instance) charger rated at 2amps and use that charger with the cable that came with it. Or find a brand name Quick Charge 3.0 charger that comes with its own cable and use that.
Other possibilities could be logic board issues (liquid damage, or even a manufacturing defect that finally showed up), or the battery itself.