How to determine the LED LCD TV backlight strip failure?

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LB-PF3528-GJD2P5C435X10-H Led Backlight Replacement kits for AOC 43 inch LCD TV

49 inch 4 LED 49UJ 6300 6916L-1315A Led Backlight Strip kits

SAMSUNG 39FH BN96-28764A BN96-29032A LED Backlight Strips for LCD TV

TCL 49'' 5 LED 4C-LB490T-YH7 Backlight LED Strip kit for Smart LCD Tv Repairing

LG 32LS3400 Parts For TV Repair LED Backlight Strips LED Bar

PHILIPS 55 inch Led Backlight Strip K55WDC2 for 55'' LCD TV Repair Parts kits

What is the best way to repair LED Backlight?

LG 47LN 6916L-1174A Led Backlight Replacement kits for LG 47 inch LCD TV