If you suspect that the battery connector has been in contact with water, or if the battery in any way looks damaged, do NOT connect the battery to the board or charger. Please contact Radinn via Submit a request immediately for more information.
To avoid water from getting into the system connectors, always make sure that you store your board and battery in a dry environment and assemble and disassemble them in dry conditions, away from water. Also regularly check the connector pins for corrosion, and your battery gasket to make sure it's not damaged.
See more on cleaning connectors here;
How to remove corrosion/oxide build-up on the battery connector