A1708 820-00840 keyboard not working after trying a bad FAN

The fan was making a noise, Replaced with an old one, I think the replaced fan had an internal short, I immediately removed the bad FAN, Replaced it with a new one... Now the keyboard is not working anymore... Rest all fine...
PP3V3_G3H_KBD - 3.4 11V
PP5V_S0_KBD - 5.1 V
PP3V3_S4_KBD - 3.3V

More likely broken trace, or knocked off components.
Check what you could damage in the replacement process.
Even using same connector, fan and keyboard lines are completely separated.
Inspect flex and KB connectors too.

Trackpad still working good?

Yes trackpad is working good , fan also working, I can see that the apple logo stays more than usual time before boot up

Recheck all the things you've touched when changed the fan first time.
Clean the connectors and inspect the pins.

The connector was bad , tried to change the connector . It was a very temperature sensitive part , I have spoiled more PCB pads... Apparently I have stopped working on this particular logic board and replaced it with another one....

Now I have a different problem..

Board brightness is keep changing... Like heartbeat every second brightness is increasing and the decreases...
Please find the video :

Is this different board?
Did you test with known good LCD assembly?

Yes its a different board, I only have an LCD that is compatible with A1706, Nothing for A1708 ...

A1706/7 LCD assembly can be used for test on A1708; vice versa is valid too.

The problem simply solved by disconnecting the LCD connector and connected again...