backlight not working after logic board replacement model A1297

MacBook Pro "Core i7" 2.2 17" Early 2011, Yosemite 10.10.5 had logic board replaced a couple weeks ago and didn't notice until recently the keyboard backlight is no longer working. Went to system preferences, keyboard, ensured everything was okay, when I depress f5 it shows on the display it is decreasing the brightness and f6 increasing brightness but no luck with lighting on keyboard. Researched and found a lot of advice indicating to do what I've already done. Nothing about issues after having logic board replaced. What am I missing? Thanks in advance for your assistance.

With the base removed and battery facing you, check that the thin brown flex cable is connected to the black socket on the logic board just under the fan on the left side. If it's not it will be under the logic board, easy to flip out and relocate if the fan is removed. If you aren't knowledgeable re dealing with this, take it back to who ever replaced the logic board. This has been the most common problem I've seen causing the keyboard backlight failure when GSX shows the logic board has previously been replaced.

techiesteve said:

With the base removed and battery facing you, check that the thin brown flex cable is connected to the black socket on the logic board just under the fan on the left side. If it's not it will be under the logic board, easy to flip out and relocate if the fan is removed. If you aren't knowledgeable re dealing with this, take it back to who ever replaced the logic board. This has been the most common problem I've seen causing the keyboard backlight failure when GSX shows the logic board has previously been replaced.

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Thanks so much, Steve. It has been driving me nuts the past couple of days. The Apple Store replaced the logic board so back to the Apple Store it will go. Thanks again.