Use a translator to navigate this Russian site; it is the most reliable source for rare MXQ builds.
The MXQ series is produced by various manufacturers using different chipsets. To ensure compatibility, you must verify your board details before flashing. Usually based on the Rockchip RK3228A or RK3229. r29 mxq lp3 v23 firmware link
A massive archive of Rockchip firmware.
A USB Male-to-Male cable (required to connect the box to your PC). Step-by-Step Installation Guide Use a translator to navigate this Russian site;
Use a toothpick to press the hidden "Reset" button inside the AV port. r29 mxq lp3 v23 firmware link
Below is a comprehensive guide on identifying, downloading, and installing the correct software for this hardware. Understanding the R29 MXQ LP3 V2.3 Hardware