I added a line to my /etc/fstab file on friendly desktop of rk3399-eflasher-friendlydesktop-bionic-4.4-arm64-20190511.img.zip

The file was empty and I wanted to add my USB to boot automatically upon reboot, I also have an SSD so I wanted to set up my fstab

It didn't like my change and now the screen is black and the green light is flashing.

So I booted from SD hoping to mount my eMMC and fix the /etc/fstab line, however.. When I boot from SD, I see:

mmcblk1 179:0 0 29.1G 0 disk
└─mmcblk1p1 179:1 0 28.8G 0 part

However I remember clearly that the mounted rootfs was /dev/mmcblk1p7,

When trying to mount /dev/mmcblk1p1 I get

mount: /opt/work: wrong fs type, bad option, bad superblock on /dev/mmcblk1p1, missing codepage or helper program, or other error.

parted says: Error: /dev/mmcblk1p1: unrecognised disk label

How do you recover from this ? And why did my adding a line to fstab break it ? where should I have done this ?

Thanks in advance.