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Do you really mean you have a "Charge". That's quite an old model and is not waterproof. See: https://help.fitbit.com/articles/en_US/Help_article/1598/
If you do have a Charge then put in a sealed bag with dry rice for a day or two. The rice will draw out any remaining water. Then try charging it again while keeping your fingers crossed.
If your fitbit is one of the models that should be able to cope with swimming then it's probably best to contact customer support via contact.fitbit.com If they can't fix it then they can check on your warranty status and advise on your options.