I got exactly the same problem last night, i did leave it without power for 10 minutes after that it did boot just fine.
I have left it off now for 6 hours to cool down without power - still '/flash/vmlinuz.gz' and this is it
I'm thinking out loud - maybe there are ways to set different kernel parameters using the bootloader setup or load a different kernel etc? If none of this works - maybe I can somehow still get access to the fs of the current flash in order to save config files as this is the most precious content I'm afraid of loosing
Guys, any help what so ever is very much appreciated!