My guess is the LED's suffer reverse bias thermal runaway when they're hot from being in a steamy enclosure and then they get a reverse 5v across them and any leakage current turns into heat accelerating the process.
My guess is the LED's suffer reverse bias thermal runaway when they're hot from being in a steamy enclosure and then they get a reverse 5v across them and any leakage current turns into heat accelerating the process.
Wouldn't it be more likely to be reverse-bias degradation of the LED junction causing permanently increased leakage current?
All LEDs are photodiodes too, certain degredations of parts or poor circuit design could lead to the display turning into a switch.