ASUS ROG laptop battery issue

asus rog gu501gm, windows 10

The old battery died, classic signs of battery death, so i bought a new-old one (oem asus but used and 'tested').

this one has a different issue... it works, and reads correctly, showing me the actual capacity, the actual % charged, the actual time remaining to charge, and works whether the ac is plugged in or not. it seems right, charges and discharges just fine.

but then SOMETIMES when i turn the laptop on... it says 0%, plugged in, charging, and just never charges. and SOMETIMES, the batteryreport reads a lower capacity than it actually has.

but upon draining the power by pressing the power button for 40 seconds, and restarting - or deleting the battery/ac drivers in device manager and letting bios reinstall them - it works normally again. until the next restart.

i know this battery could be bad too.... but before buying another one, what do i do next to verify that vs other battery components?