GE side by side GSS25WGTGBB water dispense control panel flickers/dies when pushing button to turn on light under water dispenser.

If I remove the bulb, control panel operates correctly when pushing light on button. I replaced light bulb, but did not solve issue. I replaced water dispenser control panel (WR55X10859) and the same behavior happens when turning the light on.

I removed the light bulb socket and made sure it's not shorted. I also disconnected ice dispenser solenoid (AP3963333) from control board while testing to see if maybe that's broke, but that didn't solve issue.

Background: I had the dispenser light on continuously to stop the water line from freezing. I had the light on for years and replaced the bulb several times. This issue started when the bulb went out the last time. I found the fridge with control panel flickering and removing the lightbulb fixed everything.

Also worth pointing out that I have the water line heater fix in the fridge (can't remember part number, but it is a little resistive heating element that taps into power & neutral lines for control panel and is stuck with adhesive to the area under ice dispenser.

Any thoughts what could be the issue?