2. If the seller can provide a formal invoice (not a bill or receipt), it should not be fake.
3. Log in to official website or call the manufacturer to find out how to tell. By comparing them one by one, we can roughly distinguish them.
4. Search for this product in Taobao, or use Youdao Shopping Search and Google Shopping Search to find out the market price and sales price of this product. If the price is obviously low, it should be fake.