Using Serial Console Connection to Edit Files or Change User Key in OL instances
This document assumes you have a working serial console connection to your instance and are seeing the login prompt at the serial console terminal.
You can use OCI Cloud Shell option available in OCI.
https://docs.oracle.com/en-us/iaas/Content/Compute/References/serialconsole.htm#cloud-shell
Once you have the serial console connection established Reboot the instance from the OCI Console's Instance Details page. Check Force reboot the instance by immediately powering off, then powering back on to save time as it might take longer if the OS is not in a stable condition.
Switch back to the serial console terminal pop-up window, and you will see Console messages start to appear in the window. As soon as you see the GRUB boot menu appear, use the