The R29_MXQ_LP3_V2.3 is a specific motherboard revision typically found in the MXQ Pro 4K (and some 5G) Android TV boxes, powered by the Rockchip RK3228A/RK3229 chipset. Firmware Identification & Source
The text was cryptic, but the filename matched perfectly:
MXQ_R29_LP3_V23_20190512.img r29 mxq lp3 v23 firmware link
The box should enter recovery mode and begin the "Update from SD card" process. USB Method (Rockchip Batch Tool / AndroidTool): USB-A to USB-A cable to connect the box to a PC. Install the necessary Rockchip drivers (DriverAssistant). AndroidTool v2.33 The R29_MXQ_LP3_V2
Check Official Website: The first place to look is the manufacturer's official website. Look for a support or downloads section where firmware updates are usually posted. r29 mxq lp3 v23 firmware link
Deep Report: R29 MXQ LP3 V23 Firmware Link Analysis