Doing the fault finding video I cut a faulty pixel out of the string and today cut that pixel apart to see how it failed.
Pixel is an old square 2801 series flat encased in plastic, most likely sold at the time as IP65.
It wasn't unusual for water to seep in via the cable and cause issues. This wasn't the case for this pixel.
The cause for this one can also impact epoxy filled pixels as the water/moisture seeps in via the soft silicon covering on the pixel side resulting in the legs of said LED starting to rust.
This was the end result of time to rust
this is the 8mm LED side of the PCB

This is the LED itself, the common pin is worst effected

Interestingly the component side of the board is good and appears to be epoxy coated so no damage evident to the components. I suspect that if i could connect a new led this would work

There is a little blackening of the copper wires and decent soldering.
Cheers
Phil
Pixel is an old square 2801 series flat encased in plastic, most likely sold at the time as IP65.
It wasn't unusual for water to seep in via the cable and cause issues. This wasn't the case for this pixel.
The cause for this one can also impact epoxy filled pixels as the water/moisture seeps in via the soft silicon covering on the pixel side resulting in the legs of said LED starting to rust.
This was the end result of time to rust
this is the 8mm LED side of the PCB

This is the LED itself, the common pin is worst effected

Interestingly the component side of the board is good and appears to be epoxy coated so no damage evident to the components. I suspect that if i could connect a new led this would work

There is a little blackening of the copper wires and decent soldering.
Cheers
Phil