I still try to flash the emmc. I found sometimes the very first boot just after the flash, the blue led can slow flash, meaning it boot to the system, I can login from ssh ,but not loading the desktop, second boot and so on, the blue led just stay light not flash, then can’t login from ssh. I caught one chance that it boot to the desktop just after flash, so I do a"sudo apt update" and “sudo apt full-upgrade”, the problem is gone. It can boot normally. So if you found the blue led flash maybe not even load the desktop, you can try to do a full upgrade by “putty” or any ssh software from pc. That’s just my temporary solution according to this topic5A corrupts eMMC (was 5A does not boot).