Got a black screen (DFU) after upgrading your iphone 3G S or 4 while having Tinyumbrella TTS server active? then welcome to the club. this is a commune mistake when using Tinyumbrella to evade itunes error 3194 .
Error 3194 means that itunes was not able to get the correct blobs to upgrade your iphone to the version you want. Maybe becasue it is not the latest, or because that your hosts file is pointing to the cydia server which doesn’t have these blobs either. Anyway Tinyumbrella doesn’t give up when it has no actual blobs for the phone, instead it supplies itunes with a confirmation to upgrade while will ultimately give you a nice old iBrick.
Once in this DFU black screen mode, Tinyumbrella will not longer be able to save or get your blobs, which makes resolving this situation more complex. but don’t panic. you have three solutions.
How to fix iphone black screen after upgrade?
1. upgrade to the latest IOS with itunes, your idevice will work again, but it will most probably be updated to the latest firmware and baseband making jailbreaking and unlocking almost impossible (depending in your device). this is the easy way.
2. See if you can make/download a custom version of the latest version (the version which itune suggests when you click restore) that will save your baseband and jailbreak your device. then use it to upgrade without tiny umbrella
3. Use redsn0w’s Boot tethered now to kick your device our of DFU, then get your blobs with tinyumbrella or ifaith, and see which versions you can restore to. then restore again with these blobs in tiny umbrella.