PC Not Turning On

[xNitrx]

so recently, I arrived at my native place (I still am in my native place) and I found a Dell Optiplex 990 laying around. I decided to connect all the cables, plug in a monitor and keyboard and mouse etc. and it was working for 2 days. Yesterday night I had left it on to download a few games since we have a slow wifi connection here. Today morning when I woke up to check the progress, it was turned off. I asked all of the people living in the house if they turned it off and they said no. I left it at that and went downstairs for a while. When I came back upstairs to play a few games on the pc, it wouldn't turn on at all. It didn't give any beep codes, the fans weren't spinning, nothing at all, not even the lights which indicate that the pc is on was lit. The specs are:

i7-2600(Non K or S Version)

16GB DDR3 1333MHz RAM

1TB Seagate Barracuda 7200 RPM SATA HDD

Windows 10 Pro 64-bit

 

Please help me fix this and feel free to ask for more pics/info about the pc