I spent my working years in industrial quality control, and the first thing I did before looking for a trailer was look for "what fails and why", and I got skunked with a host of problems, i.e. converter wired wrong. Our trailer however because of my involvement in its construction was simple enough for me to fix (parts left out don't go wrong) and I know how it was put together.
This does not help you unfortunately and unfortunately you need to go through teh teething process to bring it up to where it should have been coming from the factory.