New cob light power cord melting!!

I'd get a multimeter and check for a live leak around the earthing points.
With the multimeter plugged in, wiggle and flex your cables around to the extreme to see if live touches any chassis or metal.
The cable may also melt if there's a very weak connection. It may be 18awg but the weak connection may only be connected as if it's 4awg heating up specific area causing insulation to melt. Could the cable have been bent around and damaged during transport which damaged some strands??
Either way a multimeter will be your friend. With the melted cable, cut it open to see if there's any damaged it split strands.

Looking at the melted cable photo. It even looks like the cable has been pinched which may have damaged the internal insulation causing a short.
You can be more cautious by adding an RCD or a 5a mini breaker before the driver to prevent wires melting.