Don't you see 'Press any key to select [30]' ? followed by '1- Maemo 2.6.28-omap' ? If you do, Press 1. If you don't then there may be a problem with the installation of Multiboot. Not sure what your options may be then without flashing. - You could try loading the kernel manually using flasher to get the N900 to boot but this is recommended only for advanced users.