This has been posted many times but:
To debug, you need a scewdrver that fits your tama. Open up the back and takes out the batterie. Just put it aside. After, Take a really small screwdriver and unscrew those. Look around for something that says "DEBUG". Make 2 semi-circle Led marks. Do not use non-led pencils! Use real led pencils. Screw back on the one with 4 tiny screws, put the battery in and screw back up the back of the casing. Then press "Reset" and not download. Your tama is debugged!
And this is NOT recomended. It could break your tama easily.