I was performing a software update on Ubuntu 17.04, after downloading finiched, and during installation of the packages, a power failure caused an improper system shutdown. After that,Ubuntu no longer boots correctly. It starts booting, just up to the point where I should see the login screen (I even briefly see the mouse pointer), but instead of the login screen, the screen itself starts flickering on and off.
I'm guessing the issue somehow relates to a broken package regarding the GUI. I have rebooted into recovery mode and tried tu repair broken packages via dpkg. Several broken packages are identified,but they don't download, apparently because there's no internet access. I've tried the "enable network" option in recovery, but that doesn't help either.
What else can I do to get my system boting again?