I have Ubuntu running on emmc as a headless server and all worked fine until the power failure. Is there any thing I can do or test?
Connect it to a hdmi monitor (TV) and a keyboard (not wireless). Press the ESC button continuesly intill you see the UEFI firmware application https://www.udoo.org/docs-x86/Hardware_Reference/UEFI_Firmware.html There is also an issue with booting from SD card and disabling EFI, so booting in Legacy mode. Perhaps that also is possible here. https://www.udoo.org/forum/threads/boot-on-sd-card-works-only-after-ctrl-alt-suppr.8100/
I connected several monitors and TV. All with the same result (no signal). Thank you for your links. The first one is very interesting for me. I tried the issue with disconnecting the batterie but after that the same result. Unfortunately I have no wired keybord. But with the wireless one the udoo worked befor power failure. What is with the yellow LED. When does it switch to green? After booting to the BIOS of after booting a system? My LED allways shows yellow.
Yellow means there is power.... Did you press the very small power button (not the arduino master reset)? As a last resort you could try to boot from a Ubuntu live USB and see if you can get your other image repaired. You could also check the following topic where people have the same issue: https://www.udoo.org/forum/threads/udoo-x86-not-booting-yellow-status-light.7021
thanks for this link. My device acts like discribed there. (only yellow led and the cpu gets hot) I think, I have to send it back... support-ticket is opened. thank you very much