This may well be another stupid question, but I downloaded what I think is the firmware for the S17 and put it on a microSD card. I put it in and switched it on, but all I get is the two lights steadily on.
Which is the right one to flash the firmware? Maybe I'm using the wrong one. The instructions on the Bitmain site are not helpful.
That's because you are doing it wrong, you don't put a flashable firmware on an Sdcard and expect it to work! you need the special recovery files on that Sdcard which you probably don't have, how do I know you don't have it? simply because it's not available for download on Bitmain's website.
You can download the recovery files from this
link thanks to taserz for uploading them, follow the guide from bitmain, it's rather simple, if you have any questions feel free to ask.
you may need to pull the controller and shift some jumpers.
The 17 series have no jumper on them, the moment you put in an Sdcard it starts to boot from the Sdcard, the 17 series are nothing like those T9 and S9 , in fact, even the S9e and S9k are different and don't have the jumper.