if you want to keep 5.11.7 baseband this worked for me.

[glburn]

if you want to keep 5.11.7 baseband but tired of error 1600 with snowbreeze

This actually does work, i tried it restoring 3.1.2 stock ipsw before trying 3.1.3 as i have my shsh with cydia so if i made a mistake pulling the cable out i could just keep restoring the 3.1.2 software, i ran ireb and my phone was fine, i'm on O2 so you do need to be on an official sim so itunes can activate, restored to 3.1.3 and pulled cable out at same point,done the same steps and guess what it worked,ran spirit but dont need unlock as im contracted anyway but can still unlock if i want as i still have 05.11.07 baseband....believe me i have tried about 20 to 30 times with snowbreeze and kept getting 1600 error when restoring custom 3.1.3 ipsw.....100% works
these are the exact steps...
restore iphone,no need to hit shift as this is the stock 3.1.3 update
itunes reads....
"Extracting software"
"Verifying with Apple"
"Preparing Restore" may take a minute or 2
"Waiting for iphone"
"Restoring iphone software" apple logo with empty white bar appears on phone
the bar will be just over halfway complete when you get
"Verifying with apple"
then pull cable out as soon as it says "updating iphone software" and itunes gives error 9 so just close itunes

run ireb 3.1.2 3gs loop fix then activate with itunes then rejailbreak with spirit.

worked for me 100%
again try at your own risk as i did...... windows xp user with mc model 32gb 3gs which was jailbroken with blackra1n

 

[LVCIFER]

@MuscleNerd himself does not advise users to use this method.

 

[glburn]

@MuscleNerd himself does not advise users to use this method.

Don't get me wrong it's not summit I wud normally do pulling cables out but I tried in vein to get the custom 3.1.3 software on and kept getting errors, that's why I tried the 3.1.2 stock restore to test this method and it worked for me, just finished restoring from backup and putting all me apps back on and had no probs, again do this at your own risk....

 

[LVCIFER]

True, true. But now you know about the "last ditch" method that eliminates the need to pull out the cables.

I posted the link in the other thread you posted in.

 

[glburn]

I did look at the last ditch thing but to be honest the last thing I wanted to do was start deleting files from a stock firmware, I had tried snowbreeze custom ipsw on 3 different systems in my house and they all failed yet forecast said it could be done, I have new mc model but was week 37 and untethered with blackra1n, if you are jailbroken on 3.1.2 and have shsh saved you can try this method because you can keep installing stock 3.1.2 and jailbreaking, I'm not fussed on the baseband but would rather keep it the way it is and yes it did work, people have bricked their phones doing slot more than pulling the cable out.....