At this point better to start a thread on Ubuntu forums. https://ubuntuforums.org/forumdisplay.php?f=339 Already many similar questions and answers.
Also from live installer: Please copy & paste link to the Boot-info summary report ( do not post report), the auto fix sometimes can create more issues. https://help.ubuntu.com/community/Boot-Repair -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1675079 Title: 16.04 LTS Partition /boot fills up with Kernel images, gets underwear in a twist To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unattended-upgrades/+bug/1675079/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
