The LG LN series is probably the most common model I perform LED backlight repair and replacement on. Symptom is typically the backlights flashing momentarily on power up or plug in before an error is detected causing the backlights to shut down.

In most cases, the panels use strips labelled L1 & R1 and L2 & R2 with 3 black dots and thin lenses and the LED themselves can be replaced with 3V 2835 ones.

I recently encountered a 50LN5310 with a slightly different panel and LED strips. Shopjimmy indicates there are 2 different strips that could be used on this model. On disassembly, the screws for the metal bezel holding the panel in place were different and the side tabs on the panel were taped to the plastic bezel holding the diffusers. The LED strips used the thick style lenses and measuring the LEDs themselves indicated they were the standard LG 3V 2835 type. If you try to remove a strip, you will likely pop off the lenses so it is recommended to replace the LED with the strip attached to the chassis.

On the TV I worked on, many of the lenses were loose and ready to fall off. It is recommended to keep the exact same orientation and have the lens perfectly centered on the LED when gluing it back on. I have been using 5 second fix glue recently since you can adjust the lens and check it before curing it with the UV light. The glue is fairly cheap on ebay shipped from China. If the lens is not perfectly centered, it could create bright spots on the screen. If the lens falls off, it will create another bright spot.