Problems with booting

[nJoy.]

Hi, so I finally got my rockpro64 with display. Problem is that when I try to boot android image from sd card (Image is 7.1.2. for sd Cards) i don't get anything on screen. I can feel my board getting hot, I have powered it by 12v 5A power supply. Also, whenever I push buttons board reacts. I can see ethernet port LED's flashing or turning off if button is pressed for some time. LED near buttons start flashing when RESET is pushed. But screen doesn't show anything. I got it to show something once, but it disapeard qucikly thanks for your help!

[nJoy.]

Found another topic which looks like a other fellow member has a same problem. https://forum.pine64.org/showthread.php?tid=6438 I did comment there but it looks like an old topic and doubt anyone will reply there. Solution to problem isn't there also.