My final objective is to do "fastboot oem off-mode-charge 0". I've done this successfully with a Teclast P80H. But I'm having trouble with a rino3 pro. Specifically:
"fastboot devices" shows me "mt6572v1_phone fastboot" and "fastboot --version" shows me "30.0.4-6686687". "fastboot reboot" works. "fastboot reboot bootloader" works.
However, "fastboot oem " seems to never return back to my Windows Command Prompt. It seems hung. "fastboot oem off-mode-charge 0" hangs. I must control-C to get out. "fastboot oem device-info" hangs. "fastboot oem junkyjunk" hangs. It seems that ALL/ANY "fastboot oem" command hangs. ("fastboot eom" with no following command, of course, returns "fastboot: usage: empty oem command.)
Well, maybe it's not strictly oem commands that hang. "fastboot flashing get_unlock_ability" seems to hang as well.
My device is a rino3 pro. Android Settings tells me "Hardware: MTK6763" and "Processor: 8 core" and "Android 9.1" if that matters.
fastboot oem
commands are (as the command implies) oem/manufacturer and often even device specific.