If you can test the power supply, using a multimeter on the output voltages.. that would help to know.
A lot of these parts places dont even test their 'working' equipment. You probably can have them send you another one.. or get a refund, fairly easily. Ebay has shifted towards helping the user, rather than the seller these days. Ive have some jerk send me a playfield that had ridiculously raised inserts.. that were not visible from the shot angles he took.. and Ebay made him refund me. Not that Im advising cheating the system.. but if its really their fault.. or fault of shipping damages... then you should not have to eat it.
I think some of these companies expect you to do the testing that they dont have time to do. As well as expect that someone will just eat the cost rather than have the part returned.
Another thing to know.. is that the reason why a lot of these devices fail.. is due to the non-lead soldier. Unlike lead soldier, the new stuff doesnt seem to be very reliable at making strong connections. Often, its on the verge of not making contact... and with a little use.. eventually is breaks contact.
There are guys all over the place making little side-businesses of repairing these devices.. reflowing the 'soldier'.
You will have to search and research the topic. I believe some are sticking devices into toaster ovens.
Edit:
Double check by searching the model # for issues people have reported. If one issue appears the most, it may have a know bad component that needs swapping. Such as a defective cap. Sometimes as said, its the soldier issue.. that may effect an entire model.. or at minimal, a certain number of units that were from a certain lot #.