help: stuck in middle of jailbreak

[spamjammer]

I'm new to this forum.. and I'm hoping a quick response
I was jailbreaking my cell phone which is already unlocked, First I used blackra1n and when it was entering into recovery USB got disconnected .. Then it struck in Recovery mode .. and I thought, I can reload the ipsw with redsn0w but I m not able to get into DFU mode .. and even the redsn0w is not able to recognize the iphone ... I can't get past this window which says:
Now the part where you have to pay rapt attention: On the next screen you will be presented with a set of instructions. Follow them carefully:
i) Hold “Power” button for 2 seconds
ii)Then while holding the Power button, you will now have to hold Home button too for 10 seconds.
iii)Then release Power button but keep holding Home button for about 30 seconds i.e till the installation begins.

as after doing these instructions .. a pop windows says: No device detected. You probably misunderstood the instructions.
Please consult Google or YouTube for instructions on how to enter into DFU mode .. Please help ..

[keenpois0n]

if you include information such as your current model iPhone, what firmware it's running, if it is ultrasn0w unlocked or factory unlocked, and what OS you are running (Mac or pc), then we can get going from there

[spamjammer]

model iPhone: 2G
Current Firmware: 3.0
I'm installing: 3.1.2
It's Ultrasnow unlocked
PC OS: Win 7

[WTFX]

You probably just didn't get it right. Keep trying, timing is very essential. Also, you know that you got to DFU when the screen stays blank but you hear Windows's 'device connected' sound. Then you can let your finger off the home button. Good luck!

[Mes]

....ii)Then while holding the Power button, you will now have to hold Home button too for 10 seconds...

Try 8 or 9 seconds. Don't know why, but 8 works best on my 3GS old bootrom, 10 for my 3G.

[Simon]

^ I have noticed that too Mes

[Mes]

^Old bootrom too? Wonder if it's related

[Simon]

I dunno, just sometimes I have noticed 8 or 9 seconds works better than 10 for some reason on the newer devices.