It's too bad you don't have a linux box or a usb stick with a linux boot for mac,
makes it a lot harder
When you have a cross device boot like this (unless deliberatly setup), it is ripe for mis-configuration
I suspect that sda2 and mmcblk2p1 have the same label,,,, sudo blkid
So, I would say redo usb stick, change labels on stick (dosfslabel (sda1) ,, e2label (sda2))
and edit /etc/fstab (on sda2) and /boot/extlinux/extlinux.conf (on sda1) to match new labels
Since mmcblk2 has only 1 partition, it is an older manjaro install, since march?? it has been a 2 partition install
Once the usb is booting right (both /boot and / on sda) do an install on emmc
Backup anything important 1st of course, before the install
--edit--
after playing a bit more with elementary, it strikes me that as a mac user, you would find this more familiar,
the meta key is the pine key, virtual desktops are called "workspace"
I do have s3 sleep (on elementary), don't remember if I changed uboot (---I did, mrfixit uboot)
makes it a lot harder
When you have a cross device boot like this (unless deliberatly setup), it is ripe for mis-configuration
I suspect that sda2 and mmcblk2p1 have the same label,,,, sudo blkid
So, I would say redo usb stick, change labels on stick (dosfslabel (sda1) ,, e2label (sda2))
and edit /etc/fstab (on sda2) and /boot/extlinux/extlinux.conf (on sda1) to match new labels
Since mmcblk2 has only 1 partition, it is an older manjaro install, since march?? it has been a 2 partition install
Once the usb is booting right (both /boot and / on sda) do an install on emmc
Backup anything important 1st of course, before the install
--edit--
after playing a bit more with elementary, it strikes me that as a mac user, you would find this more familiar,
the meta key is the pine key, virtual desktops are called "workspace"
I do have s3 sleep (on elementary), don't remember if I changed uboot (---I did, mrfixit uboot)