I saw the bicycle light of Mrs. Nerdly Endeavours flashing brightly while the bike was parked outside. Thinking the light must have been left on, I went to turn it off but could not, though strangely enough by pushing the button enough the light would switch between flashing and constant beam modes.
After opening it up I saw that some corrosion around the button and figured the button was trashed. I was getting ready to scrap it and checked the battery voltages to see if the batteries were worth saving. They were all incredibly low, around 1.0 volts instead of 1.5. It amazed me that the light would still turn on. I decided to try new batteries and incredibly the switch started working. I guess the draw of having the LEDs on managed to disable the circuit that handles turning the thing off. Really weird that low battery voltage would make it so the light won’t turn off.