Left CTRL, ALT and SHIFT keys not working

Thanks for quick response, I checked in the recovery mode and the firmware password was disabled. So I guess this part is correct. Any other ideas?

@cyphre - what's the history of this system? Did you buy it new, was it serviced, was the battery replaced at least once?

@dan - I bought it new back in 2012, no service needed so far. I upgraded it myself in the last couple years with SSD instead of the slow hdd and 16MB of ram instead of 8MB it had. I’m also running it the OCLP patcher with Sonoma 14.4.1 installed. It was still very usable machine until now, the 3 malfunctioning keys are driving me crazy.

@cyphre - Then I would check the battery! My 2012 is now on its 5th battery with daily use and now sidelined as my keyboard key caps are badly worn and I need to replace it my self 😡

Let's install this gem of an App CoconutBattery I'm sure it's worn out and as they age they swell up which in turn press on the keyboard and the cables. Post a snapshot of the Apps main window so we can see how it is.

@cyphre - Well your Battery has at one point been replaced (2014) but you don't seem like a heavy user or you tend to use it plugged in most of the time. The batteries health is hovering around 78% while not dead it's not offering what is could.

Give this a try, with the battery out, plug in the charger and start up the system does the keys now work? Don't stress the system just check the keys using the keyboard viewer. Are they working?