I've had 4 Radion G5s fail. All were under 2 years of use, some were under 1 year of use. I have close to 30 of them running over tanks, but still a considerable failure rate. They all failed due to "open circuit", which I believe is when the controller detects a failed (open circuit) LED.
Ecotech says they inspected them all to determine root cause and would tell me what the cause was, but never did. When the fourth one failed I decided to open it up to take a look inside. What I discovered was the LED board was not properly compressed against the heat sink, and as a result the thermal paste was not making contact in certain areas. If you look at the pics below you can see where the thermal paste was applied by a machine in a rectangular shape, but was never compressed against the heat sink which would cause it to spread out into a circular shape. Heat is typically the number one killer of LEDs, so to me this is a clear manufacturing/quality issue.
I brought this up to Ecotech and they told me the thermal paste issue should not cause any issues. In response to this I sent them a link to their own video where they note how important the thermal paste is for heat transfer:
They maintained that my "open circuit" issue was not caused by this. I have a hard time believing what they told me, being an engineer and having a decent understanding of thermodynamics.
With that said, they have replaced every failed light with a new one at their expense, so I don't have any qualms other than them potentially not admitting to a manufacturing/quality issue with the thermal paste.
If I have another light fail that has this issue, and they try to charge me to repair or replace it, then I will fight this issue as I do believe there is an underlying issue here.
This seems different than the failure mode you experienced though.