This page contains some example photos that will help you identify fake YM2612 chips, primarily based on their package style. It also touches on counterfeit IC detection in general.
# TL;DR
If the YM2612s you received has the following characteristics, they are counterfeit, they will not work, and you should demand a refund from the seller.
If the YM2612s you received have the following characteristics, they are counterfeit, they will not work, and you should demand a refund from the seller.
