Buffalo provides Data Recovery services. Read about it here.
I put together a guide for creating your own recovery disk:https://buffalonas.miraheze.org/wiki/Create_Recovery_Disk_for_Intel-based_TerastationBuffalo support can also send you an SD card with the recovery image for a fee.I've also put together a custom Debian installer for these devices if you're interested:https://buffalonas.miraheze.org/wiki/Installing_Debian_on_Intel_Terastations