I have seen some similiar thing with LED things… I am not an electrician, but in my case (not 3D printer just some LED tool) was flashing sometimes, or sontinously turned on but very dimmed…
And what i suggest to try to flip the plug in the connector with 180 degree if you have the EU socket. Somehow in my case the issue was the N (neutral wire) somehow pushed some electricity to my LED tool. (sorry if it sound bullshit, but in my case somehow worked with my plug)