Laptop keyboard problems

My Dell Vostro 3500 have key Page Up always pressed.
Try https://www.keyboardtester.com/ and  wait a bit, it start to show Page Up keep pressing.
So I want to disable it. (I have removed this key both cover and plastic/rubber) but no luck.
So I tried to disable it by software.
https://askubuntu.com/questions/245333/getting-character-key-code-mappings-in-ubuntu

https://ubuntuforums.org/showthread.php?t=1218221

https://superuser.com/questions/775785/how-to-disable-a-keyboard-key-in-linux-ubuntu

Run xev -even keyboard
to get keycode pressed. My Page Up key died and I can not pressed it (press not go page up) but randomly keep pressing.

Page Down 117, Down 116, Home 110, End 115...
I guest Page Up my keyboard is 118.

I will update keyboard related problems that I've experienced later. Many interesting behaviors and symptoms. I have replaced about 10 keyboard for many Laptop and PC (always Chinese one since original not available or too expensive).

With this problem we can learn something about Key event, keycode etc. Very helpful with programming. Many time we have to deal with these domain logic.

KeyPress event, serial 25, synthetic NO, window 0x4600001,

^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~^[[5~

Show key mapping
xmodmap -pke

restart Xorg: Ctrl + Alt + Backspace

Permanent (?) disable key by edit /usr/share/X11/xkb/symbols/pc;

For example, disable PgUp key since my hardware key PgUp have been shorted (repeating randomly).

diff

<     key <PGUP> { [ NoSymbol   

<     key <PGUP> { [ Prior

Disable key using

alias fixpgu='xmodmap -e '\''keycode 112='\'''

alias fixpgu2='echo xmodmap -e '\''keycode 112 = 0x0000'\'' '\''keycode 112=NoSymbol'\'''

But it work not reliable. I don't know why. May be it moved to xkb as the post bellow said.

Ubuntu

http://xahlee.info/linux/linux_xmodmap_tutorial.html
https://askubuntu.com/questions/325272/permanent-xmodmap-in-ubuntu-13-04
https://help.ubuntu.com/community/Custom%20keyboard%20layout%20definitions?action=show&redirect=Howto%3A+Custom+keyboard+layout+definitions

http://wiki.linuxquestions.org/wiki/List_of_Keysyms_Recognised_by_Xmodmap