Restore broken firmware via netinstall

I firmware Rb951g-2hnd with openwrt and decided to upgrade to a new openwrt revision. I had 3 partitions : boot, kernel and rootfs as described http://wiki.openwrt.org/toh/mikrotik/rb951ui. Fool of me I deleted all files in rootfs. So decided to restore back routeros, I download netinstall and routeros-routeros-mipsbe-6.25rc.npk from http://www.mikrotik.com/download. Then I netboot router holding reset button, and it appeared in netinstall, I chose my routeros-mepbse file and clicked on install, afterwords it showed “Installation finished successfully” and router rebooted. Seems like everything went fine, but I still can’t access the router via ethernet ports because I don’t receive ip by means of dhcp. I also have uart port available, it worked when there openwrt was running, but now it keeps silence even on reboot. Router is still accessible via netboot. What I did wrong? Mb I should use some specific static address after firmware on a client side? I also unable to boot linux-initramfs through tftp. Is there a way I can boot initramfs via netinstall or something?

No need to have ip. Mac login works without ip address.