Really Strange Behaviour on Trackpad/Keyboard Macbook Pro / Sierra /Model 1502


My Touchpad stopped clicking. I could move the pointer around but couldn't click. Then I plugged in an external mouse. Still couldn't click but the right click worked somehow on the external mouse.
After a lot of struggling I managed to disable the Touchpad by using this command 
sudo kextunload /System/Library/Extensions/AppleUSBMultitouch.kext . Then the external mouse started to work normally.
But now the keyboard started to act strange. Some letters don't work, some do work but very slowly. Then I connected an external keyboard and it works fine.


Now I am using external keyboad/mouse and have the Touchpad disabled.

Can someone help me to make the original keyboard/touchpad work again. What is the root cause of this weird behaviour.

p.s. I have tried all kinds of reboots.
  * Command+Option+P+R
  * Option+Control+Shift
This happens all the time for various reasons. Typically, you want to disable Bluetooth and disconnect all usb devices. Then verify that you only pair or connect one device at a a time. 


  if one device has left mouse pressed down, you can’t ever get a left mouse up event from any other device.


Bluetooth interference or less commonly, faulty usb devices can overload the communications channel and you can isolate this by connecting devices one by one. 

Why can&#39;t I left click on my Macbook Pro?

The last two times I had this affect me was a second Magic Trackpad pinned under a book on a bookshelf and an old but reliable (up to when it failed) USB 2.0 hub.