When I installed an old hdd to my computer, when I then turned the computer back on I had no display output. All LEDs were in their right colors including the graphics card, all fans were spinning. I thought these things were irrelevant to each other. I think I checked my graphics card was not hanging and bending the PCI.e slot. I had no ESD band or something like that. When I tried to check my computer via Chrome remote desktop, everything looked like it should do...
I don't know what to do next.