Hello my frend. How to fix my boot problem?

[jiyong]

Probably your easiest route at this point is just to reinstall Manjaro (or your choice of other operating system) anew.

You can write a bootable image to micro-sd card and boot that, and then install to eMMC.  Or, you can remove the eMMC and flash it in another computer with an adaptor.

I have already reinstalled many times from micro sd to emms. all I have achieved is the green artifacts on the screen have disappeared and the errors remain. there are no errors when booting from a micro SD image mrfixit2001.

In that case you can try to install the U-boot from mrfixit2001.
Perhaps this thread can help: https://forum.pine64.org/showthread.php?tid=10031