I just got a new Librem 14 laptop and I am loving it except for the keyboard backlight that is not working. I’ve opened the lid and the connector is well seated. After removing it and putting it back again, I measured the voltage between GND and VCC and it is zero. Then I re-flashed the EC firmware using the bootable ISO. Also, looked in /sys/class/leds/librem_ec:kbd_backlight for any hints but nothing so far.
I did turn it on with Fn + F4. It is either OFF or 4 levels of brightness but it does not change for me. I am going to contact customer support as Frankly suggested. Just didn’t have time this week.
I managed to fix it myself—a happy story of repairability.
TL;DR: The issue wasn’t the connector or the keyboard but the cable itself. It didn’t work when twisted or bent in one position but worked in another.
Initially, I didn’t realize the backlight was off due to software settings when I measured the voltage on the connector the first time. After setting the backlight to the highest setting, I measured again and got 5V (4.99V) on the connector. At first, I thought the keyboard was broken. However, when I stripped the motherboard and connected the keyboard directly to a 5V power source, the backlight lit up.
I reassembled everything and reseated the cable in the connector several times, but it still didn’t work. Once again, I connected it to the power source, and it worked—depending on how the cable was twisted. It turned out that the default twisting of the cable under the battery had eventually damaged it.
To fix this, I added solid tape over the cable to hold it in a working position and reassembled everything. Now, it’s working perfectly!