2012 15" MacBook Pro Power Button and Keyboard malfunction.

I opened and closed, not the lid, the 2012 15" MacBook Pro half a dozen times to change out the RAM modules and to add and replace the harddrives.  I thought I am experienced not to mess anything up

Long story short, this time around when I close everything, both the keyboard the the power button acted funny, very iffy and some of the keys don't work or work intermittently and they work or don't work the next time I reboot or open and close the back cover.

I went to panic mode as this is my beloved MBP, I spent countless hours and take pride in upgrading it--quote possibility the last MBP that can be upgraded or fixed by the users.

In the end thanks to YouTube, I finally figured out what I did wrong inadvertently.

Instead of removing the battery connection like I should be before any operation, I messed up the keyboard connection.  Even the keyboard connection is protected with a metal guard with two screws.  When I finally figured that out I realized the lock lever was in the open position instead of the locked position and hence the iffy performance of the keyboard,  I locked it down and bingo all the keys work and so is the power button.

I thought it was messed up by some magnet as I also for a few seconds left the ifixit tool kit on the logic board . . . even I don't believe that's the cause but then you never know for sure.  Then I thought maybe I messed up some of the cables, but they are actually cables for the harddrive or CD-ROM (thought I changed it to another harddrive anyway), or for the keyboard backlight.

I did so many Google searches in the end, I just I found a tear down on Youtube so I know exactly which and where is the keyboard connector.  And bingo, that was the one I messed up when I initially tried to detach the battery connector.

https://youtu.be/xAHtxNVOXZI