Make sure you are downloading the exact ROM of the device you want to flash because flashing a wrong preloader, will make the device completely dead
(can't power on, can't charge and will not be detected by a computer)
Follow the instructions on how to flash the device carefully from the links below
I will not take responsibility on whatever may happen to your device.
Learn how to flash this device using SP Flash Tool from here
Learn how to flash this device using SP MultiPortDownloadTool from here