Will not boot. I have tried both Fast Boot, and Recovery.

I have many Echo 8's in my home. About a week ago, one of them had the Amazon logo, on a black screen and it was unresponsive. I have literally tried everything, I have disconnected power for hours, nothing. I have held down the mute and vol down buttons, and gotten to unit to get into Recovery mode, but when it tries to boot, it fails, and goes back to the Amazon logo. I have put the unit into Fast Boot, but it stays there for hours, and never boots. Is this thing now junk? Seems like many, many people are experiencing the same exact issue as I am, so Amazon has to be aware of this problem. I don't know if this issue had something to do with a failed update or not, but I'd love to know if anyone has been able to figure out a fix for it. Thanks for your time.