I have a 2015 MacBook pro.
It wasn't turning on since I left it off charge so I disconnected and reconnected the battery, then it turned on. However, some of the keyboard keys weren't working as a result.
Then I repeated the procedure again - I disconnected the battery again, and now even more keyboard keys aren't working.
The modifier keys (cmd, alt, ctrl...) don't work. And I can't log in (due to keys not workidng)