To install the firmware, you cannot simply "copy and paste" it. You need specific software to communicate with the Rockchip processor.
Use a toothpick to press the hidden "Reset" button inside the AV port. r29 mxq lp3 v23 firmware link
Click "Restore" (not Upgrade) to format the flash memory and install the new firmware cleanly. To install the firmware, you cannot simply "copy