[Hectic]

Main issue I can see (regardless of what gun it is) is that either the end user or ths store was using an 11.1v lipo, perhaps it was the display model with thousands of test fire rounds through it so that could explain the burnt contacts (that is what is causing the issue)
Ive run stock JG and Echo1 and VFC triggers for at minimum 1000 rounds and at max 5000 rounds with 11.1 volts and didnt have any problems. The JG had the most rounds and had some black spots but still worked before installing a fet.
On the topic, i find for the most part that surplus places arent the best place to buy airsoft guns. They carry em, so if you know what you want and the price is good then grab it but if yer looking for advice or after sale service yer normally SOL with surplus places.
If its a decent retailer you should be able to exchange or refund within 30days so long as you didnt open the gearbox. If its a decent gun exchange it. If not refund and buy a decent gun. If no resolution then consider it a cheap lesson, trigger contacts are cheap and itll give you a chance to tear it open reshim and grease it etc...