How to restore an iPhone that is stuck in DFU/recovery mode

I was given an iPhone 3GS on IOS 4.3.3, baseband 6.15.00 that required a restore to delete all the users data before the resold it. Now, as many of you reading this know, you cant just click "restore" in iTunes on a jailbroken or unlocked iPhone as iTunes will restore the iPhone with the latest iPhone iOS software, removing the lock and the jailbreak from the device. So I put the device into DFU mode and attempted a manual restoration (ctrl-click or alt-click on restore in iTunes) of a 4.3.3 firmware to the device. I then went off for a cup of tea. Unfortunately, when I returned, the iPhones screen was black, and iTunes was reporting an error. It wouldnt even charge from a wall adapter. The phone was also unresponsive to a hard reset (hold down the home and on/off button for 15 seconds). The "exit recovery" button in the application Tinyumbrella wouldnt work, and I had no SHSH blobs for the iPhone saved locally. However, it would show up as a "iPhone in recovery mode" in iTunes. After a good bit of trial and error, I finally got it working again.

1. First off, you will need to get the iphones ECID. On the mac, click on the little apple logo in the top left corner and then “About this mac”. Then click on “more info” and then “system report”. Click on “USB” in the top left and then on the iPhone. Look for “ECID”, and the number should be beside it. (you may need to have the iphone in DFU mode for this number to show up)
2. Power up tinyumbrella. Click on Manual ECID, and enter in the one that you got from the previous step. Click on the newly added iphone on the left and then “Save ALL SHSHs”. If you click on the log, it should tell you if it finds any previously backed up SHSH blobs on the Cydia server. If it doesnt, you may be able to use “iFaith” to recover the curent SHSH blob on the iPhone.
3. If tinyumbrella does find a SHSH blog on the server, it will save it to your local drive. If you click on the iPhone on the left, under the general tab, you should see a list of firmwares that the SHSH blog has been saved for. Make a note of one that you wish to restore your iPhone to.
4. Download the the corresponding firmware for your iPhone off the internet (google is your friend). If you wish, use PwnageTool to customise the firmware to your liking (unlock your phone, etc)
5.  Go back to tinyumberalla. Click on “Start TSS Server”. This will enable tinyumberella to serve the SHSH blob(s).
6. Open iTunes. Under the iphone menu, alt-click (or ctrl-click) on “restore” and select your firmware. Follow the instructions. If you have Tinyumberella open in the background, click on “log”, and you should see iTunes requesting the SHSH blob and TinyUmberella returning the blob.
7. If during the restore you get a “10**” error in iTunes, use Tinyumberella to exit the phone out of recovery mode.
8. Congratulations, the phone should be working now. If the phone needs to be jailbroken activated or unlocked at this stage, you can use redSn0w along with the firmware file.