Error: -1 means that it can't find the rockbox.h10 (or rockbox.iriver or whatever the actual file is called for h10) in the root of the player.
Also, you don't rename the rockbox folder to .rockbox. You sould at no point ever have a rockbox folder unless you've extracted the contents of rockbox.zip INTO one, in which case inside it should be the rockbox.h10 file and .rockbox folder you need. This is probably why you got installation incomplete.