I have this Chinese (important) LED sign that can be connected to a computer or it can automatically read the information (what text to show) from USB flash drive right after connecting it. It also has a power cord.
Since I have a computer far away from the LED sign I made a USB cable by using 2 USB connectors and 15m UTP cable as I read it is supposed to work. I even tested 2 flash drives and a gamepad and all devices worked properly.
Right after I connected the LED sign to the computer (using my cable) the sign showed some error in Chinese and the computer stopped working. Just black screen, as if I had unplugged the power. And that was it - no smoke, no smell, but it doesn't start anymore.
I tested the PSU on another computer and it is working just fine. Is it possible that I fried my mainboard? I mean, it's USB cable how the hell could that happen? I do not have any mainboard that I can test or borrow from somebody, so can it be something else? I have double (more like quadruple) checked all the connections, I have tried unplugging all devices and plugging them one by one. Nothing.