The errors in your XorgLog.txt are due to the "nomodeset" in your kernel command line:
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-23-generic root=UUID=a9e49865-59bc-44ce-818f-6b5b2e1c89fe ro quiet splash drm.debug=0xe nomodeset
Please remove "nomodeset" and it should work.
The errors in your XorgLog.txt are due to the "nomodeset" in your kernel command line:
ProcKernelCmdLine: BOOT_IMAGE= /vmlinuz- 4.15.0- 23-generic root=UUID= a9e49865- 59bc-44ce- 818f-6b5b2e1c89 fe ro quiet splash drm.debug=0xe nomodeset
Please remove "nomodeset" and it should work.