If I had a serial cable, what are you suggesting I do with it. Also, all of my computers are Mac's with Windows 7 via Parallel's installed in my Mac's. If I need to go to buy a laptop to do what you suggest with a serial cable, I'll do it. First, I need to know what I would do with the serial cable?
On OS X, open Terminal, then run
screen /dev/cu.usbserial- 115200
where is an actual tab keypress. It should autofill to something like /dev/cu.usbserial-A603PRMX. Plug the serial cable into a working miner and press enter, and then you should be prompted to log in (root / root). Works? Great. Now try plugging it into the troubled miner, and press enter. If you can log in, then the machine is booting, but something else is going wrong. You could try running ifconfig to see what the IP address is. If you can't log in and you see a bunch of Ç or C or ç (or something) characters appear on the screen at a rate of about one per second, that means that the miner can't boot off of the internal MMC storage for some reason. If that's the case, use a µSD card to either recover or boot.
I think the cable you need is
this type, but I can't be sure since I was sent a few directly from SPTech and never bought them myself. You might also be able to make one yourself a bit cheaper by using an
FTDI USB serial cable and soldering (or splicing) on an RJ12 connector on the other end.
The only problem is: My 17 inch MacBookPro has Thunderbolt, Fire wire 800, ethernet and USB 2.0; no 9 pin serial port. I'll need to get an adapter.