The definition of MAC address
A media access control address (MAC address) of a device is a unique identifier assigned to a network interface controller (NIC) for communications at the data link layer of a network segment. It may be referred to as the burned-in address (BIA), also be known as a hardware address or physical address.
Each NIC must have a unique MAC address, which is most often assigned by the manufacturer of a NIC and is stored in its hardware.
An example of MAC address: 88:5D:90:A1:3A:99 – It consists of 48-bit (6 bytes) hexadecimal characters (0~9, A~F), of which the first 24 bits (885D90) are allocated by IEEE (Institute of Electrical and Electronics Engineers), and the last 24 digits (A13A99) are specified by the device manufacturer.
Other formats of MAC address: 88-5D-90-A1-3A-99 or 885D90A13A99.
Necessary propaedeutics
1. Learn to burn firmware with USB cable
First of all, it is very necessary to know how to burn firmware with a USB cable, otherwise it will be hard to understand these instructions below.
From this post get to know how to burn firmware with a USB data cable:
2. Need a firmware supporting for changing MAC address
Please ask the official customer service for a firmware which can be used for MAC address changing.
According to the official release history, the name of a firmware package supporting for changing MAC address usually ends with “_Mac”, as the screenshot below.

Create and edit a license document
Locate the installation root directory of the burning tool (Usually located under the path “Program Files (x86)\Amlogic\USB_Burning_Tool”), create a new folder, rename it as “License”, then open it.

In the folder “License”, create a new text document (a .txt file), open it, copy and paste these contents below into the text document, then save it.
“88:5D:90:A1:3A:99” is a new MAC address (just for an example), which is changeable as you wish within the rules of MAC definition.
----------------------------------------------
[Group1]
start = 88:5D:90:A1:3A:99
end = 88:5D:90:A1:3A:99
used = 0
[fragment]
fragment =
----------------------------------------------

Rename the text document as “mac_ether.ini”.

Notice: If the file extension can’t be modified, follow the instruction below to uncheck the option “Hide extensions for known file types” in “Folder Options” –
Hold down Windows logo key ÿ on the keyboard, hold down “R” key, to open the Run dialog box, input “control folders” and click “OK” to open “Folder Options” dialog box, switch to “View” tab, find and uncheck “Hide extensions for known file types” option, then click “OK” to confirming modification.

The process of changing MAC address through firmware burning
Run the burning tool. If the UI doesn't show in English, follow the figure to change it into English.

Click the menu “View” -> “Select…”, check “MAC” option, click “OK”, a title bar will be revealed (Maximize the window If it can’t be seen).

After the .img file of a firmware supporting for MAC address changing is imported, the quantity of available keys for MAC will be revealed. Check “Overwrite key” option, then click “Start” button to get ready for burning.
During burning, the MAC address to be written reveals in black font.

After burning done, the MAC address becomes revealing in blue font, which indicates the writing was successful, otherwise failed.

END