ReadyNas 104 Boot from USB failed! after firmware update

Hi ukmach11

Welcome to the Community!

You should use no more than 32GB cap of USB drive and formatted on FAT32. You may also have to ready several USB drives to try.

https://kb.netgear.com/29952/How-do-I-use-the-USB-Recovery-Tool-on-my-ReadyNAS-OS-6-storage-system#Manual_creation_for_ARM_systems

To create a USB recovery drive for an ARM-based system:

You can use these instructions for recovering ARM-based ReadyNAS storage systems.
If your ReadyNAS system is x86-based, you must use the USB Recovery Tool software, which is only supported on Windows.

1. Find a USB drive with a capacity that is greater than 256 MB, but no more than 32 GB.
2. Ensure that the USB drive has only one partition.
3. Format the USB drive as FAT, FAT-32, or MS-DOS file system.
4. Make a note of the drive letter your USB drive is assigned after formatting.
5. Copy data to the USB:
   • If your ReadyNAS system is an RN102, RN104, or RN2120, copy initrd-recovery.gz and NTGR_USBBOOT_INFO.txt files from the Marvell directory onto the USB drive. Then copy to the USB drive the uImage-recovery file from the Marvell/[MODEL] directory, where [MODEL] is rn102, rn104, or rn2120.
   • If your ReadyNAS system is an RN200 or RN210 series, copy initrd-recovery.gz, NTGR_USBBOOT_INFO.txt, and uImage-recovery from the rn2xx folder to your USB drive.
6. After you prepare the USB drive, follow the directions in this guide under To boot your desktop model ReadyNAS from USB or To boot your rack-mount model ReadyNAS from USB.

Hope this helps!

Regards