When attempting to restore your iPhone 6 in iTunes, error code 4005 may appear on your screen in this situation usually means that you have a serious problem with your computer. Possible solutions and steps include:
Perform a force restart of your device: if it’s a software issue then unknown errors can come up. For this, force restart the device. If you have no choice but to restore the device, press and hold both the iPhone Home button and the Power button down together for around 10 seconds until you see the screen black out, then release them and perform the restore operation again. If it still does not work, it could be a computer issue, you need to change computers.
Check if iTunes is the latest version: Outdated versions of iTunes can present confusion into the extended level in managing antiquated and existing [...] So make sure to update iTunes to the most recent version before you use iTunes to restore your device. Grab your computer and open iTunes — search for ‘Update to Latest Version’ button on the iTunes interface 3.
Basic checking: if you want to see whether there is a hardware fault on your iPhone 6, you can check it by disassembling your device. You use a screwdriver to unscrew it, have it placed by the the iPhone lightning connector, then place the iPhone on the CPB (Circuit Protection Board) screen separator for some time, and then take out and remove the display screen and take out the motherboard with care.
We will check the Nand flash memory: In our repair, the case of error code 4005 is mainly due to the two situations, one is the iPhone CPU problem, and the second is the Nand flash memory problem. First of all, it can be used to measure the power supply voltage of Nand flash memory (such as 3V, C0604 1.8V, CO603 1.2V and C0625) with a digital multimeter to determine whether these parameters are normal. The next step is to find the resistance value of Nand flash memory to check for abnormal.
Nand Flash Reset: Once in an abnormal state, the measurement result shows that the resistance value is normal, but the error code 4005 is still not solved. Then we need to reset the Nand Flash. Requires HOT AIR PROGRAM DEVICE (QUICK 861DW Hot Air Rework Station) Best to Remove Nand flash, Place the iPhone motherboard under a stereoscopic trinocular microscope to make the Nand flash short legs of welding, Then Solder Nand flash back to the iPhone motherboard.
Test the device: Once you've done that, you have to reassemble your iPhone 6 and hook it back up to your PC. Now, try performing the restore operation using iTunes should now not show you any error codes. Go inside iOS and run all the function tests to ensure everything is working correctly.
