Help with M3 Real Card

Hi, I need some help with my M3 Real card, I bought one, and it was running fine, now, I can't get into the menu, after the health warning, and the M3 Screen, instead of the loading screen, it's all white, and just keeps in there, nothing happens... I have the last firmware (v3.1) and I don't know what to do next, it just pisses me of...

Thanks in advance. :)

Check your memory card and make sure it hasn't corrupted which does happen in many cases.

How can I check that? I tried with another MicroSD card and it didn't go after the M3DS black screen, wth the logo at the corner (after health warning, I'm going to try again...