Hi, welcome to the forum. There is a better place to ask such questions in the "
https://bitcointalk.org/index.php?board=76.0"
I had Bitmain S3 and I hope I can help you:
If you can see green LED flashing it means that miners is working. It should mean that it`s mining actualy, but for old owner who Set it up.
The factory setting is fixed: IP 192.168.99 (if I remeber well).
It`s recommended to set configuration to the DHCP.
Do you have any program which can look for active IP in your network?
Then as last hint. There is possiblity to do HW reset. Try to look in the HW part of Bitcointalk.
Hope it helps.