Black screen after every reboot (had to use toothpick again and again)

I have a Mecool KII Pro S905D.

To boot from sdcard I use the toothpick method, it boots, I install tvheadend and reboot but… it just boots to black screen. To be able to boot into sdcard I have to let the device boot into normal android, power off, and use toothpick method again.

What is my problem ?