Gareth, I am certain that you are running into corrosion damage from the salt water. I would recommend that you disassemble your phone totally. Clean all the parts with high grade isopropyl alcohol (try 90% and great) and a soft tooth brush or a similar device. You can let all the pieces soak in the alcohol. After that, '''replace''' the battery and re-evaluate for any damage. Do not forget to clean the connectors and cable ends, hope this helps. Good Luck.
+
Gareth, I am certain that you are running into corrosion damage from the salt water. I would recommend that you disassemble your phone totally. You can find a disassembly guide [http://www.ifixit.com/Teardown/Samsung-Galaxy-S-II-Teardown/5861/1|on here.] Clean all the parts with high grade isopropyl alcohol (try 90% and great) and a soft tooth brush or a similar device. You can let all the pieces soak in the alcohol. After that, '''replace''' the battery and re-evaluate for any damage. Do not forget to clean the connectors and cable ends, hope this helps. Good Luck.
Gareth, I am certain that you are running into corrosion damage from the salt water. I would recommend that you disassemble your phone totally. Clean all the parts with high grade isopropyl alcohol (try 90% and great) and a soft tooth brush or a similar device. You can let all the pieces soak in the alcohol. After that, '''replace''' the battery and re-evaluate for any damage. Do not forget to clean the connectors and cable ends, hope this helps. Good Luck.