MacBook Air A1932 No keyboard backlight after screen replacement repair

Problem description
Most cases of no keyboard backlight after a screen replacement will be due to an incorrect part being installed. The ambient light sensor (ALS) is used to control keyboard backlight. The ALS is different between 2018 and 2019 model A1932 MacBook Air devices, and are incompatible due to firmware. If a 2019 screen is installed on a 2018 device, keyboard backlight will not function. If a 2018 screen is installed on a 2019 device, keyboard backlight and true tone will not function.

Symptoms

 * No keyboard backlight

Solution
Source the correct display for your MacBook from the same year