Ubuntu 18.04 stuck in boot Segmentation fault XServer

I have a Lenovo E570 machine (with Nvidia GTX 950M) running Ubuntu 18.04 LTS.
Everything was working fine until today morning when the Ubuntu bootup got stuck at Started Gnome Display Manager. What’s interesting is that my desktop environment was accessible if I went into recovery mode and then resumed normal bootup.

Steps

After encountering this error, I have tried several things:

1. As per this answer, I removed Nvidia drivers.
2. Removed gdm3 (Gnome desktop manager) and installed it again
3. Installed and tried different Desktop managers including LightDM, SliM (and made them primary desktop managers one by one) but this did not work either (logs attached).
4. Found from logs of step 3 that this was a problem with X.Org X Server (logs are attached). Removed and installed again the package xserver-xorg
5. Installed the Nvidia drivers from Ubuntu Software Update Manager

None of the above options have seemed to work for me. What am I missing here?

My Linux kernel is 4.15.0-109-generic

Logs

1. /var/log/lightdm/lightdm.log

[+24.84s] DEBUG: Session pid=1658: Running command /usr/sbin/lightdm-session env 
GNOME_SHELL_SESSION_MODE=ubuntu gnome-session --session=ubuntu
[+24.84s] DEBUG: Creating shared data directory /var/lib/lightdm-data/osama
[+24.84s] DEBUG: Session pid=1658: Logging to .xsession-errors
[+24.92s] DEBUG: Activating VT 7
[+24.92s] DEBUG: Activating login1 session c2
[+24.92s] DEBUG: Seat seat0 changes active session to c2
[+24.92s] DEBUG: Session c2 is already active
[+272.84s] DEBUG: Got signal 15 from process 1
[+272.84s] DEBUG: Caught Terminated signal, shutting down
[+272.84s] DEBUG: Stopping display manager
[+272.84s] DEBUG: Seat seat0: Stopping
[+272.84s] DEBUG: Seat seat0: Stopping display server
[+272.84s] DEBUG: Sending signal 15 to process 1232
[+272.84s] DEBUG: Seat seat0: Stopping session
[+272.84s] DEBUG: Terminating login1 session c2
[+272.85s] DEBUG: Session pid=1658: Sending SIGTERM
[+272.93s] DEBUG: Session pid=1658: Exited with return value 0
[+272.93s] DEBUG: Seat seat0: Session stopped
[+272.93s] DEBUG: Seat seat0 changes active session to 
[+273.17s] DEBUG: Process 1232 exited with return value 0
[+273.17s] DEBUG: XServer 0: X server stopped
[+273.17s] DEBUG: Releasing VT 7
[+273.17s] DEBUG: XServer 0: Removing X server authority /var/run/lightdm/root/:0
[+273.17s] DEBUG: Seat seat0: Display server stopped
[+273.17s] DEBUG: Seat seat0: Stopped
[+273.17s] DEBUG: Display manager stopped
[+273.17s] DEBUG: Stopping daemon
[+273.17s] DEBUG: Exiting with return value 0

2. /var/log/slim.log

slim: waiting for X server to begin accepting connections Giving up. slim: unable to connect to X server


slim: waiting for X server to begin accepting connections Giving up. slim: unable to connect to X server

3. /var/log/Xorg.0.log.old

[    13.050] (II) Module glx: vendor="X.Org Foundation"
[    13.050]  compiled for 1.19.6, module version = 1.0.0
[    13.050]  ABI class: X.Org Server Extension, version 10.0
[    13.050] (==) Matched modesetting as autoconfigured driver 0
[    13.050] (==) Matched fbdev as autoconfigured driver 1
[    13.050] (==) Matched vesa as autoconfigured driver 2
[    13.050] (==) Assigned the driver to the xf86ConfigLayout
[    13.050] (II) LoadModule: "modesetting"
[    13.050] (II) Loading /usr/lib/xorg/modules/drivers/modesetting_drv.so
[    13.050] (II) Module modesetting: vendor="X.Org Foundation"
[    13.050]  compiled for 1.19.6, module version = 1.19.6
[    13.050]  Module class: X.Org Video Driver
[    13.050]  ABI class: X.Org Video Driver, version 23.0
[    13.050] (II) LoadModule: "fbdev"
[    13.050] (II) Loading /usr/lib/xorg/modules/drivers/fbdev_drv.so
[    13.050] (II) Module fbdev: vendor="X.Org Foundation"
[    13.050]  compiled for 1.19.3, module version = 0.4.4
[    13.050]  Module class: X.Org Video Driver
[    13.050]  ABI class: X.Org Video Driver, version 23.0
[    13.050] (II) LoadModule: "vesa"
[    13.051] (II) Loading /usr/lib/xorg/modules/drivers/vesa_drv.so
[    13.051] (II) Module vesa: vendor="X.Org Foundation"
[    13.051]  compiled for 1.19.3, module version = 2.3.4
[    13.051]  Module class: X.Org Video Driver
[    13.051]  ABI class: X.Org Video Driver, version 23.0
[    13.051] (II) modesetting: Driver for Modesetting Kernel Drivers: kms
[    13.051] (II) FBDEV: driver for framebuffer: fbdev
[    13.051] (II) VESA: driver for VESA chipsets: vesa
[    13.079] (II) modeset(0): using drv /dev/dri/card0
[    13.079] (WW) Falling back to old probe method for fbdev
[    13.079] (II) Loading sub module "fbdevhw"
[    13.079] (II) LoadModule: "fbdevhw"
[    13.080] (II) Loading /usr/lib/xorg/modules/libfbdevhw.so
[    13.080] (II) Module fbdevhw: vendor="X.Org Foundation"
[    13.080]  compiled for 1.19.6, module version = 0.0.2
[    13.080]  ABI class: X.Org Video Driver, version 23.0
[    13.080] (WW) Falling back to old probe method for vesa
[    13.080] (II) modeset(0): Creating default Display subsection in Screen section
  "Default Screen Section" for depth/fbbpp 24/32
[    13.080] (==) modeset(0): Depth 24, (==) framebuffer bpp 32
[    13.080] (==) modeset(0): RGB weight 888
[    13.080] (==) modeset(0): Default visual is TrueColor
[    13.080] (II) Loading sub module "glamoregl"
[    13.080] (II) LoadModule: "glamoregl"
[    13.080] (II) Loading /usr/lib/xorg/modules/libglamoregl.so
[    13.083] (II) Module glamoregl: vendor="X.Org Foundation"
[    13.083]  compiled for 1.19.6, module version = 1.0.0
[    13.083]  ABI class: X.Org ANSI C Emulation, version 0.4
[    13.083] (II) glamor: OpenGL accelerated X.org driver based.
[    13.101] (EE) 
[    13.101] (EE) Backtrace:
[    13.101] (EE) 0: /usr/lib/xorg/Xorg (xorg_backtrace+0x4d) [0x55f3d6f7f8cd]
[    13.101] (EE) 1: /usr/lib/xorg/Xorg (0x55f3d6dc7000+0x1bc669) [0x55f3d6f83669]
[    13.101] (EE) 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7f8341fac000+0x128a0) [0x7f8341fbe8a0]

>     [    13.101] (EE) 3: /usr/lib/x86_64-linux-gnu/libEGL_mesa.so.0 (0x7f83393f3000+0x129cc) [0x7f83394059cc]
>     [    13.101] (EE) 4: /usr/lib/x86_64-linux-gnu/libEGL_mesa.so.0 (0x7f83393f3000+0x1b19e) [0x7f833940e19e]
>     [    13.101] (EE) 5: /usr/lib/x86_64-linux-gnu/libEGL_mesa.so.0 (0x7f83393f3000+0x216df) [0x7f83394146df]
>     [    13.102] (EE) 6: /usr/lib/x86_64-linux-gnu/libEGL_mesa.so.0 (0x7f83393f3000+0x1ac0b) [0x7f833940dc0b]
>     [    13.102] (EE) 7: /usr/lib/x86_64-linux-gnu/libEGL_mesa.so.0 (0x7f83393f3000+0x16b7d) [0x7f8339409b7d]
>     [    13.102] (EE) 8: /usr/lib/x86_64-linux-gnu/libEGL_mesa.so.0 (0x7f83393f3000+0x16bc5) [0x7f8339409bc5]
>     [    13.102] (EE) 9: /usr/lib/x86_64-linux-gnu/libEGL_mesa.so.0 (0x7f83393f3000+0x10948) [0x7f8339403948]
>     [    13.102] (EE) 10: /usr/lib/xorg/modules/libglamoregl.so (glamor_egl_init+0x10b) [0x7f833e845c9b]
>     [    13.102] (EE) 11: /usr/lib/xorg/modules/drivers/modesetting_drv.so (0x7f833f083000+0x9dc9) [0x7f833f08cdc9]
>     [    13.102] (EE) 12: /usr/lib/xorg/Xorg (InitOutput+0xc08) [0x55f3d6e60288]
>     [    13.102] (EE) 13: /usr/lib/xorg/Xorg (0x55f3d6dc7000+0x56cd3) [0x55f3d6e1dcd3]
>     [    13.102] (EE) 14: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xe7) [0x7f8341bdcb97]
>     [    13.102] (EE) 15: /usr/lib/xorg/Xorg (_start+0x2a) [0x55f3d6e07b8a]
>     [    13.102] (EE) 
>     [    13.102] (EE) Segmentation fault at address 0x55f3d90000f7
>     [    13.102] (EE) 
>     Fatal server error:
>     [    13.102] (EE) Caught signal 11 (Segmentation fault). Server aborting
>     [    13.102] (EE) 
>     [    13.102] (EE) 
>     Please consult the The X.Org Foundation support 
>        at http://wiki.x.org
>      for help. 
>     [    13.102] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
>     [    13.102] (EE) 
>     [    13.133] (EE) Server terminated with error (1). Closing log file.