my s3 is broken on arrival.... only one chain working...
any idea on fix ?

Open the cover of S3 and check the cables and connectors are fine.
Check for any component damage or loose or burns.
If everything so far is fine then, disconnect one blade from the control panel.
Also remove pci power cable from the disconnected cable.
Run the S3 and check if the blade or chain is displaying in S3 miner stats page.
If no blade is showing, connect the disconnected blade back and disconnect the already connected blade.
{
Now run the S3 again and check if the blade or chain is displaying in S3 miner stats page.
It should. Then disconnect the cable connecting this working blade to the disconnected blade and run S3.
Now check if the chain is shown. If not shown, you blade which is now connected is damaged.
}
else if blade is shown
{
Then disconnect the cable connecting this working blade to the disconnected blade and run S3.
Now check if the chain is shown. If not shown, the blade now connected is damaged.
If shown then your other cable connecting blade and control panel is faulty.
}
If in all the above steps no blade is shown your control board is damaged.
If your found one blade is damaged via the above steps, try reapplying thermal paste. A rare change for survival.
Contact bitmaintech for RMA if blade is damaged and request for a new cable or buy or build your own.
/edit
Copy paste your System and Kernal Logs here or PM.