Kindle stuck on white triangle topic

When I press power on my 1st gen kindle, I get the "Kindle Fire" screen followed by a dimmer screen that has a white triangle.
Device is not recognised by PC, either Win 7 or Ubuntu.
Shorting the connection inside as per this thread doesn't work.
KFU doesn't work.
ADB can't connect in any mode.

I'm thinking I have a brick??
Device has stock ROM, recovery, etc, AFAIK it hasn't been modified.

Thanks in advance for any help, pointers, etc etc.

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