Try this
Set the theme to default
Turn off 3DS
Turn back on 3DS
Select theme
Go to CHMM and try to install a theme
If that doesnt work try this (This one worked for me)
Set the theme to default
Go to system settings and change the language of the system
Restart 3DS
Change language back to...
@SylverReZ, I also heard one of the Prince of Persia games was so unfinished that it required the "24/7 online" drm so a puzzle could be done and the game could be finished. And that when the Ubisoft servers were closed the (cracked) game was impossible to finish or something like that
I like that games can be fixed after the fact, hate that it's being abused via beta tests... And DLC... I was a 7800 owner back in the day and loved Impossible Mission, turns out I couldn't beat it because it was actually impossible lol