my quess is theres something wrong with the board... from what your describing and the leaving it over night and working again makes me think there may be a bad cap someplace on the board thats not discharging properly so when going to restart its still seeing voltage present on the board thats interfering with the power up checks... computer motherboards do that as well at times and usually can be fixed by recapping the bad caps but in the case these days its not worth the time to troubleshoot the board as they are pretty cheap.
I recently purchased a RockPro64 and am setting it up with an eMMC module and having the same issue.
I've tried armbian Streth and Bionic, ayufan's Stretch and Bionic, DietPi, and mrfixit2001 Debian. All have the same issue and some cannot even complete setup as a reboot is necessary.
The board's power LED will stay lit, but the while LED will not come back on and it can only be rebooted after removing power or a combination of hard reset and power buttons.
More or less same here, was running stable (with reboots!) for several weeks but seems to have crashed yesterday when plugging in a USB hard drive. Since then no luck in getting a sign of life:
- green DC LED is on when plugged in (white LED for running board never worked)
- when plugged in ethernet port starts blinking (mostly only amber LED, sometimes also green LED)
- no output on the HDMI port
Long press on the power button turns it off (at least LEDs on ethernet port turn off), only green DC LED stays on.
Already tried a different SD card with new system with the same results. My only idea left is to try jumper cables for the boot order, otherwise I'm out of ideas. So in case there is anything else I could try, please let me know.
Are you using the same power supply for both RockPro64 boards?
If so the culprit could be the power supply and not the board.