Ubuntu 16.04, 4.15 HWE kernel, driver 430.26, login loop (bug report included)

Bug report will be uploaded
nvidia-bug-report.log (1.61 MB)

If you installed the driver from ppa, please check if this applies:

Yes, I installed it from ppa. Unfortunately, I have found this post and re-linked the libGL.so.1. However, login loop still exists

It’s an Optimus notebook, yet you created an xorg.conf. Please delete it, then make sure the package nvidia-prime is installed:
sudo apt install nvidia-prime
switch to nvidia:
sudo prime-select nvidia
and reboot.
I don’t know if this alone will make it work because there seems to be a problem with the igpu’s firmware:

i915 0000:00:02.0: Direct firmware load for i915/kbl_dmc_ver1_01.bin failed with error -2

Might be that this was still blacklisted in 16.04 but try installing it nevertheless:
sudo apt install linux-firmware