Actually its kind of easy to determine the exact factory firmware used on the device. Most of these Chinese devices use the same chip but just different names like XBO, CMX, XBN etc. All what you need to know is just the id on the board then you are one step closer to the firmware you are looking for.
Just follow the instructions below and you will know the exact firmware to be used on your device.
RomKingz is not responsible for any outcome using this steps
Do at your own risk!!
Screw drivers & some courage
On a normal, when you take off battery, you will see the brand name and model number. But when theres none, or the device is unknown, do the following below
-Turn off the device and take off battery
-Use the screw drivers and courage in you to unscrew the device (be careful if you are not use to this)
-Now when you have successfully loosen the device, you will see a white sticker on the board
-On the sticker you will see the name of the firmware used on the device
-Now just do a search on that name using google and see results
-Download the file and flash the device with it.
I know most of these unknown brand firmware are not really found online but I will soon start uploading them. Especially those that will work on high grade Sony Xperia Clone devices (Copy). Mostly for new names like XBN, CMX, etc. Just Stay Tune