MacBook Pro Shift key problem My MacBook Pro with Retina display has the following problem:


Left Shift Key not functioning
Sometimes Shift is on automatically and when restarting, will restart in safe mode


What I've done:


Try using USB keyboard, the problem persist (always in Shift e.g press 8 will output *)
Restart holding OptionCommandRP, get option to reinstall and three others
Restart holding OptionCommandOF, the problem is gone but not for long (first time, it takes a day to happen again.. now, every 30 minutes or so)
Install Karabiner-EventViewer, the press the Left Key definitely give no response; when my MacBook Pro in Shift, the log shows Shift flags for every key pressed.
Reinstall macOS, seems not solving my problem


How can I stay out of safe mode, and use the functionality of shift keys?
I have the same issue with MacBook Pro A1502 EMC 2875 on macOS 10.12.6 fresh installed and previous 10.10.

I also see graphics glitch on PWD logon switching to the desktop, and it's sluggish.

I re-seated ribbon cable and reset SMC. It worked for a while, then it returned.

I believe the keyboard got light liquid damage, so I'm changing it as a test.