I tried updating it on a DS again. The update worked fine (got the update complete message and the file was deleted). I'm still getting the error on the 3DS though. I'm starting to think it may be an issue with the contacts. Every so often when I stick the game in, the 3DS doesn't recognize it...
It's a console error. Tells me to hold the power button to turn off. I've only had it a day but it seems like as long as I get it to boot once using the fridge trick, it'll keep booting as long as I don't take it out.
Does anyone else have any experience with this? I've got the same issue. The DSTwo works fine in a DS but gives an error on the 3DS. If I stick it in the fridge for a minute or two, it boots up fine.