Thank you very much for your help.
I am stuck here,where is sysand options?
Go to “SysNAND Options”, then “System Save Dump”, then select “Dump configsave.bin
BIG PROBLEM
I followed the guide untill step 9.I think it didnt make a nand back up because my sd was small(only 2 GB).
I continued to step 19 but it said it didnt find any files.So i updated again to 10.2 in order to use another sd and try the guide from the beggining but the 3ds doesnt open...