sorry mate for my late reply, did u take off the pass code and put it airplane mode, then try it with airplane mode off , also make sure the screen lock isnt on choose never just for the jailbreak, try running the jailbreak in admin mode, different lead all these are possibilities mate , another possibility , was your sons iphone updated OTA from the hand set
1004 jailbreak failed: Caused by problems on your iDevice. Quit all background apps and try again.
other issues u might encounter
1001 device disconnected: Don't do anything on your device during the jailbreak and keep it plugged in. Use certified cables.
-1002 device is password protected: Turn off your passcode.
-1003 data corrupted: Re-download the jailbreak tool from taig.com and make sure you have a good connection.
-1004 jailbreak failed: Caused by problems on your iDevice. Quit all background apps and try again. Restore your iDevice and try again if it still won't work.
-1005 device has Find My iPhone turned on: Turn off Find My iPhone.
-1006 device has already been jailbroken: What are you thinking.
-1007 device is not activated: Activate your iDevice and try again.
