Logic board not pulling power properly

I have a water damaged 6S and I’m a bit stuck as to what to do next.

I’ve tested the following by isolating components with known working ones:

Battery - working ok

Charging port - Working ok

Logic board - Boots and works ok when connected to a charged battery but won’t pull power to recharge the battery

When I first booted the phone up after cleaning, the phone charged normally and was pulling 0.42A but I unplugged it and now when plugging the phone in it only pulls 0.05A for a couple of seconds then drops to nothing.

Any advice on where to look next greatly received!!