could be the fan,i've seen dust get in there and there's a screen that the fan blows air through to cool down the electronics,so if the fan is bad it's not cooling down your board and that's why the light flicker,how old is the unit,sounds like the board is damaged from over heating most likely from the fan and i looked up the model number and you can't get that board anymore,if the board is bad you could get it rebuilt,i just helped someone else with the same problem the board is discontinued,you have to have the board taken out,draw up a wire diagram and send the board out to have it rebuilt,when they send it back you reinstall it,and wire it.
https://www.appliancetimers.com/appliance?model=gbd307pdt7
maybe if the fan motor gets changed out the board won't over heat anymore and won't give you a problem but it doesn't sound good.i think the board will also be an issue