I just downloaded and installed newest security update (2018-06-**) for my device. After restart screen just went black. When i plug in to charge it, it vibrates, so it is working. Tried force restarting with Power + VolDown, it restarts, but you can only barely make out even the samsung logo when restarting because the backlight does not light up. I tried going into system recovery mode but i just can't see anything... What should i do now?