I wrote this out for people in the Tamagotchi Livejournal Community, and since all the tips and tricks are gone, I thought I'd post it here. ^_^
Warning: If you damage your tamagotchi by doing this, it's your own fault. No one's making you debug, and I'm not responsible if you don't do it right. This guide DOES NOT WORK on anything but a Tamagotchi Connection V1 and V2. Connexions, En-Tamas, etc. do not debug. I have no idea whether the V3s do or not, but I would advise against messing with it unless you know what you're doing.
That said, on to the good stuff.
Step 1. Unscrew the back of your tamagotchi the same way you would to change the batteries. Remove the battery. Don't lose the battery or the screw! ;D
Step 2. You will need a very small screwdriver. Unscrew the four little screws that hold the case together. They're really small, so don't lose them.
Step 4. Pry the two halves of the case apart. Do it VERY GENTLY so you won't break anything. It may be a little difficult getting it apart by the keyring, but just keep at it.
Step 5. You will see a circuitboard. Don't mess with anything on it just yet. Make sure the side that holds the battery is facing you.
Step 6. There are two half-circles with the word DEBUG next to them. With a blunt pencil (not a mechanical pencil, that will just break) scratch over those two half-circles so you get some pencil lead between them.
Step 7. Put the tamagotchi back together. Remember to put the battery back in. (duh)
Step 8. Press the reset button and choose "reset", not "download." Set the date, time, and your birthday like normal, and the baby will hatch. By pressing the A button at the initial baby screen (where it tells you the gender), you can scroll through all the tamagotchis and even some that never became official tamagotchis (testers, i guess). You can reset it and do this as many times as you want.
Info: When you press the C button in debug mode, it speeds up time so you can grow your tamagotchi very quickly. The time will go back to normal whenever your tamagotchi needs anything, so you don't need to worry about that. To un-debug, just use a cotton swab or a small eraser to rub off the pencil from the two half-circles.
If you have any questions, please ask and I'll do my best to answer you!
Warning: If you damage your tamagotchi by doing this, it's your own fault. No one's making you debug, and I'm not responsible if you don't do it right. This guide DOES NOT WORK on anything but a Tamagotchi Connection V1 and V2. Connexions, En-Tamas, etc. do not debug. I have no idea whether the V3s do or not, but I would advise against messing with it unless you know what you're doing.
That said, on to the good stuff.
Step 1. Unscrew the back of your tamagotchi the same way you would to change the batteries. Remove the battery. Don't lose the battery or the screw! ;D
Step 2. You will need a very small screwdriver. Unscrew the four little screws that hold the case together. They're really small, so don't lose them.
Step 4. Pry the two halves of the case apart. Do it VERY GENTLY so you won't break anything. It may be a little difficult getting it apart by the keyring, but just keep at it.
Step 5. You will see a circuitboard. Don't mess with anything on it just yet. Make sure the side that holds the battery is facing you.
Step 6. There are two half-circles with the word DEBUG next to them. With a blunt pencil (not a mechanical pencil, that will just break) scratch over those two half-circles so you get some pencil lead between them.
Step 7. Put the tamagotchi back together. Remember to put the battery back in. (duh)
Step 8. Press the reset button and choose "reset", not "download." Set the date, time, and your birthday like normal, and the baby will hatch. By pressing the A button at the initial baby screen (where it tells you the gender), you can scroll through all the tamagotchis and even some that never became official tamagotchis (testers, i guess). You can reset it and do this as many times as you want.
Info: When you press the C button in debug mode, it speeds up time so you can grow your tamagotchi very quickly. The time will go back to normal whenever your tamagotchi needs anything, so you don't need to worry about that. To un-debug, just use a cotton swab or a small eraser to rub off the pencil from the two half-circles.
If you have any questions, please ask and I'll do my best to answer you!