I'm having problems putting my iPhone 3G into DFU mode I have upgraded my iPhone 3G from iOS 3 to iOS 4.2.1 using the iclarified Redhook for windows tutorial.

Upgrade has gone fine but I cannot get Redsn0w (v0.9.6b6) to recognise the DFU state. Every time I restart in DFU mode, I get the following error:


  "No Device Detected. You probably misunderstood the instructions.
  Please consult Google or YouTube on how to enter DFU mode"


Please note I had problems entering DFU following the Redsn0w instructions (i.e. start from off then: hold power 2-3s, power &amp; home 5-10s, then home 13s) as these do not work  from power off on my iphone 3g. If my iphone is off and power button or power &amp; home button are held, iphone immediately starts in recovery mode (with icon). 

I can enter DFU (black screen) by having phone on, holding power button and slide power off on screen, I then release power button 5-6s after phone has switched off (per DFU instructions on google utube etc), phone enters DFU mode but not picked up by redsnow 

Any suggestions welcome
To enter DFU mode:


Make sure the phone is on and iOS fully loaded, and iTunes is closed.
Plug the phone into your computer using the Apple proprietary cable.
Once plugged in, turn your phone off by holding the power button.
When the phone is completely powered down, perform the following
sequence:


Hold the power button for 3 secs.
Without letting go of the power button, press and hold the home
button for 10 secs.
Without letting go of the home button, release the power button for
another 10 secs.



Ignore what's happening on your screen, just time the sequence. If you are not succeeding, then you are not timing the sequence properly. There is only one way to enter the device into DFU mode. The one provided by Redsn0w is the correct one.