I just bought a refurbished iPhone 8 with 256 Gb.. Everything looks fine... except that the battery drains really quickly. If I charge it up to 80-85% and then leave it on the table, without using it (screen turned off, obviously), the battery will have drained in less than 24 hours.
This is with IOS 15.2 installed but without any apps except the stock ones; in fact, without even a SIM card or iCloud configured, just with Wifi connected to the local network.
When I connect it to the Mac to check it using coconutBattery, it says that the refurbished battery is fine:
14 cycles, 389 days, "Desay Corporation" (which is what my original iPhone 8's battery also says, so it must be the same part that Apple uses)...
Is there any reason why I shouldn't return it? Is there any obscure reason why a new battery might give trouble during the first cycles, or why IOS 15.2 drains battery much faster while idle...? Anything other than the obvious explanation that it's defective?