How can I fix water damaged phone it flashes on and off

perfectheartforyou, there is always hope:-). Just remember that water damage is the toughest to repair since any part may have failed. Even if you do everything right, it may still never work again. But there is hope. At this time my advice to you would be to no longer try to start or charge your phone. Remove the battery, and disassemble is right down to the logic board. If you can tell us what make and model phone you have, we may even have a repair guide for it. Clean everything with isopropyl alcohol (90%+) and a soft brush, including all connectors and cable ends. Use this guide to see how to clean it. It was written for a 3G but all the points are pertinent to your phone as well. Check for any burned or missing components. You may have to repeat this step a couple of times. Once it is cleaned, reassemble it and replace the battery, then reevaluate for any real damage. Right now, everything will only be a guess, and the longer you wait the more corroded it will get. Hope this helps, good luck.