Freeze during bootup

If mouse or any below still works

1. Try Alt+F2, run xkill
2. Try Ctrl+Alt+arrow to switch to another workspace and try to open System Monitor
3. Or, use ctrl+alt+F1 etc. switch to char counsel, and use commands
   1. sudo stop lightdm...... wait.......sudo start lightdm (restart X and kill all running application)
   2. kill X as super user restore desktop BUT KILL YOUR CURRENT SESSION

If nothing works, try the (Alt+Sys+) "REISUB" magic key

The Magic System Keys when the system REALLY freezes

http://en.wikipedia.org/wiki/Magic_SysRq_key

Further analyzing: https://wiki.ubuntu.com/X/Troubleshooting/BlankScreen

https://wiki.ubuntu.com/X/Troubleshooting/Freeze

Checking boot log

https://askubuntu.com/questions/765315/how-to-find-previous-boot-log-after-ubuntu-16-04-restarts

$ journalctl --list-boots

$ journalctl -b-1

I suspect this is related to suspension, cause it seems to occur after I close the lid of my laptop then re-open it.

To edit boot parameter:

• During boot, press and hold left SHIFT (someone suggested but haven't been successful) or quickly press ESC
• Menu show up, press "e" to edit

Recording things may help:

https://askubuntu.com/questions/1030867/how-to-diagnose-fix-very-slow-boot-on-ubuntu-18-04 (lots of assumptions and diagnosis, worth reading)

• Add "noresume" after "linux..." line
  • to make it permanent edit grub file
  • however it prevent from resuming a hibernated system
• Someone suggests "nomodeset" to fix a common Navdia driver issue - however this does not seem to relate to my problem
• Diagnose - `systemd-analyze blame` `systemd-analyse time` systemd-analyze critical-chain
• 
  

https://www.dedoimedo.com/computers/ubuntu-beaver-slow-boot.html (long, with detailed analysis)