I shelved my first de10-nano for a while after lots of fruitless troubleshooting, I couldn't figure out what was wrong with it.
But seeing all the progress made the last couple months on making the HDMI output more compatible with various displays I gave it another go and still couldn't get it to work. It showed more signs of life though, and I saw the menu for a split second before I lost video again.
Finally, last week I broke down and ordered a spare de10-nano board. I am happy to report that the new one works flawlessly with my self-built memory board and everything. Currently playing around with ao486 after memtesting my ram board
I still wonder what is wrong with the old de10-nano though, it is still able to boot the included linux image and I get video from that one.. If I run the most recent MiSTer image and looking at the serial console output it looks like it loads the RBF fine and it responds to keypresses since i can see the OSD debug messages. I just don't get HDMI video. Maybe I should get started on building an IO board to see if VGA would work
How did your broken de10-nanos die Sorgelig? Have you been able to repair them?