When you boot moonshell and it shows an error, it means two things. You need to delete the logbuf.txt which can be located in the moonshll2 folder and put the moonshll2 folder on the root of your memory card. The Moonshell2.nds can be placed ANYWHERE as long as the moonshll2 folder is on the root. Hope this helped. =)
Credits: somerandomguyO_O, Denetsu3000 (for the logbuf.txt info)
Credits: somerandomguyO_O, Denetsu3000 (for the logbuf.txt info)