There is another question in my mind, is it will work if i use another TS-2RZH48T12D recovery USB on this same device model? or it would not work, because different s/n?
I can create recovery usb form another same model device.
---- 1 hour later ---
I see this word during create the "recovery drive" USB;
"This USB drive only recovers this TeraStation. When booting from the USB drive, all settings will be restored on their defaults, any data will be deleted, and all drive will become part of a RAID 0 array."
The answer, No is not. But I will try it.. let's see what happen.
-----1 week later ---
It is work, I use the "recovery drive" USB from another TeraStation 7000 with same model/spec and hdd size (12 bay).
1. Create "recovery drive" USB disk from another TeraStation 7000. (you can read in manual on page 145)
2. Shutdown the Terastation that you will recover and then insert the recover USB into USB port on the TeraStation.
3. Plug the monitor and keyboard or you may use KVM to monitor the process.
4. Power on the TeraStation and repeatedly hit F7 until the blue boot device menu appear.
5. Select the USB flash disk on boot menu, then the TeraStation will be began the recovery about 10 minutes. It will reboot then shutdown by it self. (no need action from you, just wait until the TeraStation shutdown completely)
6. After shutdown, remove the USB and turn on the TeraStation.
7. Then you go... login with default user.
Thank you so much for @1000001101000 and Buffalotech forums.
**noted: now you know how important the recovery drive is