I bought a RN104 back in July 2015 and it's been happily sat serving files up for a while now. Periodically I'll login and do whatever updates are waiting. Most recently (maybe 6.9.5) I did the update and now it's broken. It boots to "Boot from USB failed" on the screen. I found some forum threads and figured I'd make a USB key with firmware on. I did that, and booted from it. It booted into recovery then shut down. I did as instructed and removed the USB key and started up again. Now it's back to "Boot from USB failed" and I can't get past that.
I think a good few people have had "issues" with the USB recovery procedure in the past. It seems a little "finicky" to get to work, at times.
Your issue does sound like a problem with either corrupt OS firmware on the flash chip of the flash chip itself being bad. I suggest that you try the procedure a few more times with different USBs as well. It is important that the USB is perfectly healthy as well.
You data is very likely total unharmed. It is possible to re-load the NAS OS firmware image onto the flash chip manually via the NAS CLI, but that should not be attempted unless you know exactly what you are doing.
Give it a few more go'es with the USB recovery procedure and if you cannot get further it is best advised to reach out to Netgear support.
I've tried a dozen times with 3 different USB keys. Part of the problem is I don't know what a successful flash should look like. It certainly boots via USB, and puts up a message about USB Recovery. However I don't know if I should see some progress indicator, a success message or what?
