My Nas does not boot and gives me an error. All the forums I find tell me to upload the firmware from usb. My question is but does this affect the data stored on the disks? I don't want to lose 8 tb of data. Thank you
That is an issue with the btrfs file system on the disks - which almost certainly won't be solved with a USB recovery. Salvaging your data will instead require some form of data recovery.
Try powering down and removing the disks (labeling by slot). Then power up, and confirm that you see a "no disks" status on the LCD.
If you can connect the disks to a Windows PC (using either SATA or a USB adapter/dock), then it would be good to test them with vendor tools - Seatools for Seagate; Lifeguard for Western Digital.
