Nanopi R6S no longer displaying HDMI output, Unbrick failing

[ppanon]

I was working on installing OpenBSD 7.7 on a Nanopi R6S. I was using the EDK2 firmware build on an SD Card and the OpenBSD installer on a USB Key to install the O/S on the EMMC. Things seemed to be working fairly well in that I was able to boot the installer using the HDMI framebuffer device (set tty fb0, followed by boot sd0a:/bsd.rd) and run through the install to write the O/S to the eMMC. However after rebooting, I seem to have lost all HDMI output. I don't even see the FriendlyElec firmware splash screen either. I tried to go through the brick recovery steps using maskrom mode and they seem to work at first.

# upgrade_tool ld
List of rockusb connected(1)
DevNo=1 Vid=0x2207,Pid=0x350b,LocationID=131 Mode=Maskrom SerialNo=
# upgrade_tool db MiniLoaderAll.bin
Download boot ok.
# upgrade_tool ssd
List of supported storage
No=1 FLASH
No=2 EMMC(*)
No=3 SD
No=4 SD1
No=5 SPINOR
No=6 SPINAND
No=7 RAM
No=8 USB
No=9 SATA
No=10 PCIE
Input No to switch,Quit press <Q>:qq
# upgrade_tool ef MiniLoaderAll.bin
Loading loader...
Start to erase flash...
Download Boot Start
Download Boot Success
Wait For Maskrom Start
Wait For Maskrom Success
Test Device Start
Test Device Fail

It looks like the device test is failing. Is there some way to obtain more information on what device tests are failing? Is the device permanently damaged or are there some other steps I can try to follow to recover the firmware so it will support the HDMI again?

[jonathonhooper]

It doesn’t sound like the device is permanently damaged-this is usually a firmware/bootloader issue rather than hardware failure. Losing HDMI output (even the splash screen) suggests the boot chain on eMMC may be corrupted or incomplete. The “Test Device Fail” during maskrom recovery often points to a mismatch or unstable loader rather than a dead board. You could try using a different or updated MiniLoader/EDK2 build, or fully reflash the original FriendlyElec firmware image to eMMC to restore a known-good state. Also double-check power supply and USB cable stability during flashing, as interruptions can cause these errors.