I recently received a stepdown in the post that was DOA. The seller offered a full refund but I thought I'd see what was wrong with it and whether I could bring it back to life.
First step was to check the fuse. That was fine. Next I needed to get inside it. It has security screws in it. The screws and required bit are pictured below.
I tested the fuse in its holder. No continuity. I opened up the holder to properly inspect it. It's shocking low quality! The holder is plastic with a thin foil overlay. You can see in the pic below that the foil had been worn away, breaking the circuit.
A friend desoldered the fuse holder and inserted another. It means I'll have to open it up if the fuse goes but I'm happy to get it up and running.