Try using Iprep instead of JungleFlasher, I had the same problem and i was using the xbox to power the drive too. Make a bootable usb and put your CFW and OGFW on it. Once you make a bootable usb,it should create a file called "Backups". Make a folder in the backup folder named "1234567 12345" or you can use the consoles serial number so you know which file has what FW. Rename your Original FW dump to SAMOFW.BIN and rename your Custom FW to SAMCFW.BIN and put them in The "1234567 12345" folder. Reboot your PC with the USB inserted and load the boot menu. Select USB and Iprep should start running, type "SAM 1234567 12345 w". Next, iprep will ask you a few questions, answer "no" to the 1st and 2nd questions and "yes" for the 3rd. At this point iprep should be trying to detect the drive, if you're getting a status of 0x51 or 0x80 you need to power cycle. Once, you power up it should detect and ask you to power cycle again and press any button to continue. Now the drive will be erased and the banks 0-1-2-3 are being written. Done.
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