I encourage you to read article from thekikgen

https://github.com/TheKikGen/MPC-LiveXplore/wiki/MPC-internal-controller---Midi-aspects

However on the force it's a bit different.

when doing amidi -l you have your midi interfaces

root@force:/home# amidi -l

Dir Device    Name
IO  hw:0,0,0  Akai Pro Force Public
IO  hw:0,0,1  Akai Pro Force Private
IO  hw:0,0,2  Akai Pro Force MIDI Port
IO  hw:1,0,0  AudioBox USB 96 MIDI 1

by sending sysex message you can lit or not some pads , here is an exemple :

 
amidi -phw:0,0,0 -S 'F0 47 7F 40 65 00 04 43 06 00 00 F7'

Below are the hex Values on the force :

In the bytes of the color , it seems that MSB are for brightness, and LSB for the color.

As an exemple

low intensity on pad 
amidi -phw:0,0,0 -S 'F0 47 7F 40 65 00 04 33 01 01 01 F7'

mid intensity on pad 
amidi -phw:0,0,0 -S 'F0 47 7F 40 65 00 04 33 11 11 11 F7'

higher intensity on pad 
amidi -phw:0,0,0 -S 'F0 47 7F 40 65 00 04 33 21 21 21 F7'

In addition, i'm currently trying to understand sysex message for the small OLED screens.

As an exemple this sysex message will draw something on the second OLED screen on the force :

amidi -phw:0,0,0 -S 'F0 47 7F 40 0B 00 73 01 00 01 27 56 00 20 10 08 00 00 01 00 00 00 00 08 00 02 01 00 40 20 00 00 04 02 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 40 20 00 00 00 02 01 00 40 00 00 00 04 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 7C 50 24 11 07 60 01 79 20 48 22 0F 40 04 13 79 00 F7'  

Someone has put an article on this messages but i did not understand everything, so I'll try by myself. Below is the article : https://blog.segger.com/decoding-the-akai-fire-part-3/