Finding the exact firmware for the board can be tricky because "MXQ" boxes are often clones with varied hardware. However, this specific board version is tied to the Rockchip RK3228A chipset. Most Reliable Resource
While official links frequently go dead, community-maintained repositories are the most reliable sources for this board version: Stock Firmware Dump: A technical repository for the R29-MXQ-LP3-V2.3-00908 build is available on r29 mxq lp3 v23 firmware link
Flashing firmware wipes all data. Proceed at your own risk. R29-MXQ-LP3-V2
specifically cover the R29 board with the Rockchip 3228A processor and offer contact information for flashing assistance. Community Forums : While older, the LibreELEC Forum provides insights into mixing firmwares and using the Amlogic Customization Tool for related MXQ hardware. Flashing Requirements Proceed at your own risk