Hi guys, today I needed to disconnect all cables from the PC tower to do something with it, and later on reconnected them. However, now the monitor doesn't seem to be working properly, as it gives the "going to sleep" message then a black screen. I have checked inside the tower and nothing seems to be loose. There are two cables connecting the monitor: power cord and HDMI cable. I have tried using a VGA cable, but that doesn't work either. Any help would be appreciated!