Recently I have wondered if I had gotten fake Apple products. Mainly, because I purchase Apple MacBook Pro for myself and my family. To you, the worst of all would be that I sold you an Apple Fake MacBook Pro. SO< even if you don’t purchase from me, go here: Obviously if you bought the products from Apple or an Apple Store, I would say that you’re most likely 99.999999% safe. But, this is mostly when you purchase from places like eBay–and I’ve done this a lot!, Amazon, and other online e-sales.
https://checkcoverage.apple.com
Enter the serial number and check the validity of the purchase date and other details.
It would make me feel better for your sakes, that you don’t get any Fakes!
If the MacBook doesn’t switch on, then look for the serial number in the box and verify it on these websites
If for whatever reason, your MacBook doesn’t start then take note of the serial number on the box. Every serial number partner is different for MacBook, MacBook Pro, and MacBook Air. To validate the same, visit https://support.apple.com/en-in/HT201608 for MacBook, or visit https://support.apple.com/en-jo/HT201300 for the MacBook Pro. To validate the model of a MacBook Air then visit https://support.apple.com/en-gb/HT201862.To know whether the second-hand or refurbished MacBook is stolen or not, always ask for the serial number first 
Before you start negotiating on the price of an old MacBook ask for the serial number first. If the seller doesn’t provide the serial number, cancel the deal right away. Note that buying a stolen MacBook can land you in serious trouble.
Don’t buy any locked Macbook even if the seller tells you that he/she will unlock it after full payment
If you are buying an old MacBook from someone, ensure that it’s unlocked and fresh. Never buy any locked device as it could be a stolen one and the owner might have remotely locked it.
To know the actual age of the old MacBook model that you are buying do this
Visit https://support.apple.com/en-in/HT201608 for MacBook, or visit https://support.apple.com/en-jo/HT201300 for the MacBook Pro. To validate the model of a MacBook Air then visit https://support.apple.com/en-gb/HT201862. Check the respective model number to know the actual age.
If you are buying an Old MacBook, start it to ensure that there are no firmware passwords
Ensure that MacBook boots up to the desktop first. Then restart it. When the Mac OS is booting (when you hear the startup chime music) hold the Alt/Option key. If there is a firmware password, the previous owner should remove it.
Check the condition of the battery of the old MacBook model
Open system information (if you don’t know how then search for the term ‘system information’ by clicking on the magnifying glass search button on the top right side). On the left, browse down to power and click on it. Note the battery serial number and capacity to check the authenticity of the battery. To know the battery’s life, note the ‘Cycle Count’ under ‘Health information’ of the battery. I can personally attest to this because labor and the cost of that specific part and labor can run you over $100. That could be a headache.
Every MacBook model has a maximum battery cycle count, compare it with the official website to know the exact battery life
Compare the ‘Cycle Count’ of the old MacBook battery with the maximum cycle count of the any MacBook model by visiting this website https://support.apple.com/en-us/HT201585
If you are buying an old MacBook, check the optical drive
Insert a DVD to check whether the optical drive is working or not. In new MacBook models, there is no optical drive. I personally haven’t had this issue, because as a computer repair professional, I have backups. But, it’s definitely a great idea!
Run Apple Hardware Test (AHT) by visiting this website
To know the exact condition of the MacBook hardware, visit this website https://support.apple.com/en-in/HT202731 if the MacBook model is prior to June 2013, then visit this website for Apple Hardware Test (AHT) https://support.apple.com/en-us/HT201257
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