I changed the battery in my s710 with no problems.. The biggest issue is finding the battery.. I called 5 watch shops and many other places and could not find a battery..
I ended up buying 2 on ebay and then did it myself.. If you have the right screwdrivers its very easy..
They use a model CR2354. Here is the link to seller, I had them checked and they were full strength..
http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WD1V