Oh, also your kernel is stuck in recovery mode:
[ 136.650] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-39-generic root=UUID=8a9d54df-bf77-4277-990d-781804a2250b ro recovery nomodeset
which will cause graphics problems.
To fix that, reboot and then hit Esc as soon as the purple screen appears. Now navigate the menus and choose a regular kernel that does not have the recovery option.
Oh, also your kernel is stuck in recovery mode:
[ 136.650] Kernel command line: BOOT_IMAGE= /boot/vmlinuz- 4.15.0- 39-generic root=UUID= 8a9d54df- bf77-4277- 990d-781804a225 0b ro recovery nomodeset
which will cause graphics problems.
To fix that, reboot and then hit Esc as soon as the purple screen appears. Now navigate the menus and choose a regular kernel that does not have the recovery option.