Can't boot from SD Card with TWRP

jactra

The reset button is normally at the end of the A/V port. Use a toothpick to reach\press it.

1. Burn a SD card with your preferred image.
2. Unplug box from power.
3. Insert SD.
4. Press and hold the reset button.
5. Plug power back.
6. Keep holding reset for a few seconds until the logo appears on screen.
7. Wait for LE to install.

Quote from The Coolest

1. Burn a SD card with your preferred image.
2. Unplug box from power.
3. Insert SD.
4. Press and hold the reset button.

I'm afraid that box (Mecool M8S PRO) does not have the Reset button...

got exactly same setup. to boot from SD I used the update app from the nexus rom. burn your sd as usual, plug the usb pen drive with the same update.zip file you used to flash the rom, open update app and select update from zip (locale I think), let the box reboot, while rebooting pull out the usb pen drive. it works for me. on similar boexes (s905x, etc) it worked with just any .zip file, but in this particular soc i found that it needed the official rom update file, or it will give some error message. hope this helps.

Quote from jactra

With it there is installed TWRP Recovery. I would like to test LibreElec (boot from SD Card, not installing) and I have little problem. The only way I can reboot to recovery is "terminal emulator" method by using "reboot update" command. I don't have reset or menu button, don't have "update" app. So I used terminal emulator to reboot recovery but after this it runs TWRP. What should I do to boot from SD Card in this case?

Did you try a simple app from Google Stor, "Reboot to LibreELEC" ? It should reboot from Android and boot from SD card.

With it I solved a similar problem on an X96Mini with broken reset button...

I use this app to boot to my TWRP "recovery.img". After I make some major changes in Android I just stick in my SD card containing TWRP recovery.img and use "Reboot_to__LibreELEC" to boot TWRP and save my complete Android images.