hi Gents
I think i followed the guide.
- I used BalenaEtch to flash a SD card, with Debian image from your website.
- Plug in the SD card;
- Power up.
It still boots into the Android, from internal eMMC.
Is there any way to forcibly boot from SD?
Can NOT boot from SD (Debian installed)
Please refer to this guide. In short the SoC will first check eMMC for bootloader, and Android’s bootloader will also first boot from eMMC, so microSD is ignored in this process when both conditions are met. You need to wipe eMMC’s bootloader for SoC to try booting from microSD.
thanks for reply;
i think I followed each step in your guide, in the RZ USB BOOT HELPER，I can load factory-loader.img , but the “erase” button keeps gray and unactive.
Seems it did not get into fastboot mode.
(attached)
We are investigating this issue, as well as validating microSD boot for various distros.
So is this a known issue? Can you reproduce the same issue?
I tried 5 times, none of them succeeded in erasing the emmc. 
Please provide some solid alternative approach.
Gentlemen, can you please reply to above question?
It means a lot if you declare Radxa can not boot from SD card with Debian installed.
My colleague told me that our images should be bootable from microSD card. I’m currently busy with some other projects so unfortunately I couldn’t test it myself. My suggestion is to try erase the eMMC in Linux then boot from microSD. You can use some live image to boot your PC into Linux without installing a new system.
So I did a bunch of testing and confirmed that our images can work off microSD. You do need to wipe off eMMC first before it can be booted. Since your “Erase” button is grey, I’d like to see if you can install fastboot tool and check the output of fastboot devices once you loaded factory-loader.img. At this moment I’m quite confident that we can work out an solution for you.
When your “Run” button is grey, can you check the device manager window if the zero is detected?
We just published a new guide to help you wipe off your eMMC’s bootloader, so you can boot from microSD. The guide assumes a Linux system since the tools are more available on that platform, but you should be able to learn how to use their Windows counterpart in our maskrom guide.
Please let me know if you are having any difficulties, and if this guide helps solving your problem.
It’s getting into new issue.
It does not recognize a few arguments and fails to run through you new guide.
And seems only “sudo fastboot erase bootloader” can work. Which might take effect.
Now my Zero can boot into Debian on microSD, but weirdly it can also boot into OS from internal eMMC by removing the microSD.
test@ubuntu:~/Desktop$ fastboot devices
AMLG12A-RADXA-ZERO fastboot
test@ubuntu:~/Desktop$ sudo fastboot unlock
fastboot: usage: unknown command unlock
test@ubuntu:~/Desktop$ sudo fastboot unlock_critical
fastboot: usage: unknown command unlock_critical
test@ubuntu:~/Desktop$ sudo fastboot fetch bootloader bootloader.bak
fastboot: usage: unknown command fetch
test@ubuntu:~/Desktop$ sudo fastboot erase bootloader
erasing ‘bootloader’…
OKAY [ 5.714s]
finished. total time: 5.714s
test@ubuntu:~/Desktop$ sudo fastboot erase bootloader-boot0
^C^C^C^C^C^C^C^C # Can NOT finish till 20 minutes so I tried to hardstop.
No; Windows “devicemanager” will show a new device “USB download gadget”
Let me record each of my steps, for your information.
seems this is due to missing the driver of “USB download gadget”on windows, which causes the “erase” button unactive.
reasonable?
probably you can send me the driver on windows for me to try?
This is because you loaded the wrong binary.
This is because you still have some bootloader installed on your eMMC. You can refer to this guide to wipe those additional bootloader.