If it stays stuck on the boot logo for more than 15 minutes, you have bricked it. You will need to short the CLK and GND pins on the motherboard to force mask ROM mode (out of scope for this guide).
Power off the head unit completely (disconnect the car battery or the main harness). Connect the USB A-to-A cable from your PC to the unit's designated "update" USB port. Hold the "Reset" button (tiny hole on the front face) and plug in power. The PC will detect "MTK USB Port." android yt9216bj00012v001 patched
Many patched versions contain improved CANBUS drivers for better car compatibility (steering wheel controls, AC display). Risks and Precautions (Important) If it stays stuck on the boot logo