If you jumper 12V to the light it should help you zero in on the issue or eliminate some potential issues. Iíd start at the light itself to satisfy yourself the light is ok. If the light tests ok, pull the wing an jumper 12 V to the wing-root connector. If itís dim, youíve got a bad connection between the connector and the light - and possibly the ground, as Rob indicated.
Bob Y - builder 12iS E-LSA
N569TT first flight 2/9/2020