Well, as I mentioned, my NAS is bricked. It can't load OS saying wrong ramdisk image format, ramdisk image is corrupt or invalid. Simply said, code which should be transferred to the memory got incomplete because DRM update process was interrupted by power outage. Thats why there is ethernet connection and also reset not available. U-boot loader is intact, this allows me to use built-in serial console on PCB to connect via USB TTL converter using putty, establish communication with tftpd32 for loading kernel and ramdisk images into the memory, thats all I know. But I am just facing some issue during this process, because not really skilled, so I try to get help somewhere.