I updated to 3.0.0-5U without even thinking about any issues with the M3i Zero. I downloaded the new F_CORE.DAT file (
http://down.gbalpha....CORE_v3.0.5.zip) from
http://www.handhelds...load_M3DSR.html I copied the new file to my microSD card and tried to run it and it failed. However, I looked at the "
M3i Zero firmware Upgrade Manual(*.pdf file)" and it mentioned plugging in the M3i Zero using the included cable. I plugged it in and the LED flashed for about 25 seconds. I put it into my 3DS and it works perfectly! One thing I noticed, though, is that the ROM icon changed from Hello Kitty to SpongeBob, so you could look for that to see if yours was updated successfully.