I have a RPi 3, with Stretch written onto a freshly formatted FAT32 card. I am able to get to the terminal command line and raspi-config, but I am not able to expand the filesystem, change the wifi settings, or save any other setting. I get a "read only" filesystem error when trying to edit and save wpa_supplicant.conf.
Following some directions on another forum, I used the "mount -o / rw" command. This resets the pi into desktop instead of terminal, and seems to now make the filesystem writable and the settings saveable. Something about this process, however, breaks a lot of the other functionality (terminal, for instance) and seems to corrupt the filesystem.
Any ideas on why my system is stuck in "read-only" mode on initial startup?