Does your Antminer S4 powers on and the Fans start to spin, but the front LCD screen remained blank or simply the back light is on but nothing showing on the screen?
Is your LAN Status LED by the Ethernet Connector shows no sign of lights?
There are 3 major causes to this.
Most likely the problem is caused by the LCD Screen or S4 Control PCB area behind the LCD screen inside the case.
First, the data cable between the LCD screen and the Control PCB are loose or not connected well.
Second, The Antminer S4 uses a Beagle Bone Black's Linux Operating System on the MicroSD card. The MicroSD card may not be seated well in the card holder/slot. The MicroSD card slot is located in the RED CIRCLE within the example photo. You can push the card in with a finger and it will pop right out. Please take the card out and reseat the MicroSD card back into the slot.
(Example Photo: )
Third, your MicroSD card data may have been corrupted from the static electricity, power surge, unexpected power loss or other reasons. In this case, you have to restore the MicroSD card to the factory default setting. (Re-imaging) You will be needing a MicroSD Card Read/Writer.
If you need assistance, restoring the corrupted microsd card, our tech support staffs are available to you via telephone at 844-248-6246 Option 2 (USA County Code is 1) or Live Chat.
For remote assistance, please have a remote access software called TeamViewer ready. It is a free software and you can download a copy form http://www.teamviewer.com
If you have any further questions, please do not hesitate to contact us.