My aunt's iPhone 4 was jailbroken the day it was bought. And about last month, she updated it. Suddenly the screen went blank only the apple logo was showing. She can't fix it with iTunes because she forgot her account. Is there any way to fix this without iTunes?
- You tried to update a jailbroken iPhone without restoring it first.
- The iPhone won't boot anymore
- You cannot just upgrade a jailbroken device without restoring it as new device.
- If you restore the iPhone via iTunes it should be fixed. (You don't need any Apple ID for this, unless the iPhone is already iOS 7.* and iCloud enabled)
You can try to restore it without the help of iTunes. Make sure you have the latest firmware, which you can download from here.
Then download the latest stable release of redsnow here
You can follow the tutorial here on how to restore you iPhone to the latest firmware. Please note that this will erase all your files in your device, which includes the jailbreak. Hope that helps.