Problem with Brother BAS-415 / Help Please!

I own a Brother BAS-415 which has been working fine for me for several years. Recently, I was cleaning the bobbin compartment to make sure the thread was being fed properly from the bobbin. I turned on the machine and hit the Start button once and the needle bar started inching(?), it moves up and down at a steady speed without stitching and the plate doesn't move side to side either. It only moves up and down at that constant speed. When I pressed the Emergency button, the machine didn't respond. None of the buttons on the panel seemed to register so my only option was to turn the power off.

I'm not sure whether it's an issue with the mainboard or with something else but I would like to know how to stop the needle bar from inching continuously. Any help from someone with expertise with this particular machine or knowledge about this type of situation would be greatly appreciated!