Flashing firmware typically requires an external hardware jig (USB-to-Serial adapter or specialized MStar USB Debug tool).
: If you require different versions, such as v4.5.3 or v5.0.8, they are hosted on technical forums like Master-TV.net and Software Informer. Key Features and Capabilities mstar isp utility v475 download link
Mstar ISP Tool Upgrade Instructions | PDF | Usb | Menu (Computing) such as v4.5.3 or v5.0.8