Some bosses can seem hard, when you have no clue what strategy you'll need. The magnetic Golem is actually not even hard to kill at all... If you know how that is.

So, for your viewing pleasure, here's how to kill him (used the search function cause was too lazy to type it all out):

If you kill him fast enough, there's nothing special you need to do but if you can't kill him fast enough...
After you attack the boss for a while orbs will appear along the wall. Stay inside the blue orb to stay alive. These orbs always go in the same pattern every game, so you can memorize them.

So, I'd suggest you try the above first before burning your expensive flatscreen TV