All fine !

問題

As for many users, my 3GS ran out of battery too easily and often, and I was fed up by Apple's repair costs...

修理

I was worrying about such an operation, but following carefully your guide step by step, I didn't encounter any serious issue. Just kept my cats from jumping over the table where all these small parts where lying ;-)

アドバイス

Take it slowly, and try to avoid any disturbance. It's so easy to break a small part, or to forget connecting something...