Here's another thread I helped with back in 2020, same model as yours and same problem:
We have a Whirlpool WRF736SDAM14. The lights were flickering and going dim intermittently for about a month then they all stopped working one day, and have not worked since. The door switches seem to still work since the water in door doesn't work when the doors are open and the audible chime...
At the top LED board on the ceiling of your refrigerator J1 Pin 1(yellow wire) to J1 Pin 3(white wire) you should be getting 120 volts.
On the main control board P2 Pin 1(yellow wire) to P1 Pin 2(white/black wire) is where that power comes from to that LED board, you should be getting 120 volts between those when the doors are open.
Here's the LED board on the ceiling of your refrigerator section ceiling for your model:
CNTRL-ELEC W11033329 / AP6039953 made by Whirlpool
Here's the main control board for your model: W10854027
Here's the power control board for your model:
Electronic Control Board WPW10453401 / AP6021648 made by Whirlpool
Take that voltage readings from that too and see what you get:
Both the main control board and power control board are located in the very back of the refrigerator exterior wall, behind its cover, the power control board is the smaller one, the main control board is the larger one.