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when i rec its emergancy mode
jailbreak redsnow 0.9.6rc8

Redsnow is a tethered JB. Thus, every time the phone reboots it will hang at connect to itunes logo. Instead, use Greenpoison for a untethered JB. And, if it's stuck at the emergency call screen, you need to activate the phone through itunes or hackivate the phone.
 
Redsnow is a tethered JB. Thus, every time the phone reboots it will hang at connect to itunes logo. Instead, use Greenpoison for a untethered JB. And, if it's stuck at the emergency call screen, you need to activate the phone through itunes or hackivate the phone.

Now what can i DO
 
Now what can i DO

1) Run Greenpoison and make it a untethered JB.
2) If you need to hackivate, run Redsn0w 0.9.6 b5 or above, click on “Install Cydia” option only and follow the on-screen instruction. Redsn0w will not only install the missing Cydia but also hacktivate your device.
 
1) Run Greenpoison and make it a untethered JB.
2) If you need to hackivate, run Redsn0w 0.9.6 b5 or above, click on “Install Cydia” option only and follow the on-screen instruction. Redsn0w will not only install the missing Cydia but also hacktivate your device.

All done Step by step
but set same hang on logo
 
I am afraid you might have to do a restore, and then, JB again. But, to restore to 4.2.1, you need to have saved 4.2.1 SHSH blobs. W/o it, you can only restore to 4.3. And, if you haven't previous saved your 4.2.1 blobs, you won't be able to do it now. To be sure, download and run Tinyumbrella. Make sure your iPhone is detected. Click on "Save my SHSH...". Afterward, what SHSH blobs were you able to saved? Whatever you were able to saved are what you can restore to.
 
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