I've been trying to update to 5.1 and I get an SD Firmware error of --.----- I've formatted my SD Card multiple times to FAT32 and still get that error. I am using Disk Utility on my Mac to format the card, which wasn't an issue when I updated it to 5.0
The main reason I'm wanting to update to 5.1 is for the soft mode hack and nag screen bypass. Which I'm unable to find for 5.0 at the moment.