Could be. The boot problem is not a Manjaro problem, it's a preboot problem. It just doesn't see the eMMC occasionally, but most of the failures are it hanging

Could be. The boot problem is not a Manjaro problem, it's a preboot problem. It just doesn't see the eMMC occasionally, but most of the failures are it hanging trying to load the u-boot secondary stage off of it. SD card boot works all the time though.