Hi i have been given an iphone to fix that is getting stuck on the boot screen where it has the colour faults at the top (the one you get after jailbreaking). It also is not being detected by the computer. I have tried putting it into DFU and that does nothing.
Yup, then it must not be in DFU mode.
DFU mode instructions;
Step 1. Turn off iPhone
Step 2. Hold down the power and home button.
Step 3. When you see the Apple logo, release the power button but continue holding the home button down (about 15 to 20 seconds).
Step 4. Open iTunes and wait for it to tell you that it detects iPhone in restore/recovery mode.
Recovery Mode:
Step 1 Turn off the device by holding down the Sleep / Wake button until a “slide to power off” message appears, then sliding the slider.
Step 2 Press and hold the Home button, then connect the iPhone to your Mac with the USB cable while continuing to hold the Home button.
Step 3 Wait until iTunes displays a message that it “has detected an iPhone in recovery mode“, then let go of the Home button.