Due to the incomplete partitioning your internal card has bad partition table and some broken file systems. Can you surf the net to manually download rootsh here: http://repository.maemo.org/extras/p...sh_1.8_all.deb to the N900 directly and try if tapping it in the file manager will install it?

@elros34: Do you mind switching to a more verbose state and elaborate on the usage of rescue os to give some help, please? Personally never touched it...