On Sun, 19 Jan 2020 13:41:33 -0800 (PST),
wrote:


When it is powered on, it should flash all the buttons for a second,
and then only the functions that are active, should remain lit.
If you press a button, it should send a CAN msg and corresponding
light behind the button should turn on/off.

The broken keypad still keeps its control abilities 100%, but you
have to work blind, as the leds behind the keys don't light up at all.
No powerup test flash, no working lights, nothing, but when you press
a button, the specific tool is activated, so CAN connectivity seems ok.

Good. The problem is therefore isolated to whatever is driving the
LED lights. I count 18 LED's. On board B back, carefully remove
the black plastic insulator so that you can trace the LED wires.
Try to determine which chip, resistor pack, or whatever is driving
the LED's.

I can't read the part number off the photos. The two TCL5943 seem to
be likely cause of the problem. However, I can't find anything
with Google for that part number. Are you certain that they are a
TCL5943 or are they something else? Can you find a data sheet?
Also, I find it odd that the device would require 32 outputs to
drive 18 LEDs. Are there more LEDs somewhere as most of the outputs
on both chips seem to go somewhere.

Plug everything back together and check for power and switching
waveforms (for LED dimming) on all the TCL5943. I would be more
specific if I could find a data sheet on this device. Basically,
start with any LED and trace the signals and DC back through the
TCL5943 chips, and on to whatever powers the chip.

My guess(tm) is one of the chip resistors on the PCB is acting as
a fuse, and it's blown. I looked for something that looked like
a fuse such as "F1" reference designator, but found nothing.

Link to photos: https://drive.google.com/drive/folde...Df?usp=sharing

Good luck.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558