How can I fix my Huion light pad? (tracing light-box)

I have a Huion A3 light pad. The backing on one corner is loose which has caused (or been caused by) the piece that the power cable plugs into to come loose, so unless it is squeezed closed it doesn’t work.

The plug bit comes out still attached to a small black square piece with two little metal connections - can I fix this myself? I’m slightly more handy than this post makes me appear!