First, let’s clarify terminology. A "flash tool" is a low-level software utility that writes firmware (the operating system) directly to the device's memory chip. For Nokia smartphones running Android (from HMD Global), the official tool is often a variation of , OST LA (Online Service Tool Launcher) , or SP Flash Tool for devices with MediaTek chipsets.
Install the Nokia USB and MTK VCOM drivers on your Windows PC. nokia 23 flash tool link