Moises Becker " started on", "no way to charge it" it is always a bad idea to do any of the prior to a water immersed device. You want to treat this like any other water damaged device.
The major issue you will run into is corrosion damage. Salt Water will get your components to corrode very severely very quickly. The first thing I would do is to disassemble it by following this guide. Post some images of what you see with your question. For that usethis guide Take a careful and close look at all components and connectors. Truly assess the damage. Look for major corrosion, evaluate the pins in the connectors etc,.Take a look at all connectors as well as cable ends. After that I would suggest that you clean it a couple of times in sterile water, no drinking water. (that might have helped right after it got submerged in the sale water). Use a soft brush and clean it very, very thouroughly with the sterile water. Once you got the gross contamination cleaned, use 90%+ isopropyl alcohol and clean your parts some more. For a proper cleaning, use this guide. It was written for a iPhone 3G but it is still pertinent to your device as well. I can not stress the importance of a good cleaning enough, so do it over and over while replacing the alcohol after each cleaning. Do not use compressed air for the cleaning since that can drive liquid as well as corrosion particles into areas that will cause trouble later on. Do not use drinking water, if you need to use water, use sterile water. Also you do not need to leave it dry for a day. Isopropyl alcohol in the higher concentration will evaporate quickly and dissipate the water. The importance here is the cleaning. With the month long corrosion, I suspect plenty of damage to the pins, that may be irreversible through cleaning. After you got it cleaned properly you do want to use a new battery Even with all this, there is really only a small chance that your Flip will work, but I definitely would give it a try. There is no other way to get anything of the memory unless you get it to start up and be recognized on your computer. Hope this helps, good luck.