I was having a similar issue with “Le Potato”, as well as the device will not reboot if I am using the OTG port. While attempting to triage the latter issue, I tried “apt install watchdog” after reading How to Shutdown Libre Computer AML-S905X-CC Le Potato and https://www.kernel.org/doc/Documentation/watchdog/watchdog-api.txt. When nothing is connected to the OTG port the system now reboots as expected. You may want to give it a try.