If possible, remove the board from the case and the battery from the board. Dry the board completely using a hair dryer. If the board was exposed to salt water, rinse the board with fresh water and then dry the board. You may try inserting a new battery and downloading the data. If you are unable to access the data, or see any sign of corrosion or tarnishing on the board, contact the place of purchase for a return number. The data may be retrievable, and the data logger may be repairable. Charges will apply and are dependent on the amount of damage.