I'm also interested in what that "secret door" contains...
So here's my save file (compressed no$gba) with all puzzles unlocked...
http://qshare.com/get/147677/Professor_Lay...ge_USA.SAV.html
1. Phoenix Wright: Ace Attorney
2. Phoenix Wright: Ace Attorney - Justice For All
3. Phoenix Wright: Ace Attorney - Trials and Tribulations
Apollo Justice, the 4th game, is coming out in the US in 2 weeks.