Below devices support to professional flash:
iPod Touch2, iPod Touch3, iPod Touch4, iPod Touch5, iPod Touch6
iPad1,iPad2,iPad3,iPad4,iPad Air,iPad Air2,iPad mini/2/3/4,iPad Pro
iPhone3G,iPhone3GS,iPhone4,iPhone4s,iPhone5,iPhone 5c,iPhone5s,iPhone6,iPhone6 Plus
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Steps to enter DFU mode:
1. Keep device in normal mode or recovery mode, plug USB cable (please don't use USB extension cable)
2. Hold HOME button, then hold power button until screen is blank
3. Release the POWER button after about 4 seconds, but keep holding the HOME button for about 10 seconds
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14:33:46 Friendly reminder:
14:33:46 Please make sure device turned off 'Find My iPhone'
14:33:46 The device will can not activated without Apple ID after flash, in case device turned on 'Find My iPhone'
14:33:47 Method to check: Settings -> iCloud -> Find My iPhone
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14:33:47 Please connect USB cable to apple mobile device, make sure you are in DFU mode14:33:59 User stopped operating, error at line 14825
14:33:59 Failed to flash
14:33:59 If the device doesn't exit current mode
14:33:59 Please hold the HOME and POWER buttons for about 10 seconds
14:33:59 Flash and jailbreak of apple device, please visit official website of 3uTools 3uTools | iOS jailbreak & flash tool
14:33:59 Elapsed Time: 00:00:12
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Activation of device used in:
Use for activating the new unactivated device
Use for activating the flashed unactivated device
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Activation supports below device:
iPad1234minimini2mini3mini4AirAir2Pro
iPod Touch23456
iPhone3G3GS
iPhone44s
iPhone55c5sSE
iPhone66 Plus6s6s Plus
iPhone77 Plus
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Steps of activating device:
1.Insert the SIM card into device(iPad.iPod ignore this step), SIM card of corresponding carrier needs to be inserted into the locked device
2.Please make sure device under the normal status
3.Please connect your device to your computer using the USB cable
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14:51:18 Checking AppleMobileDevice service14:51:18 Waiting connect in normal mode14:51:18 Retrieving device's information14:51:18 Unique Device ID: 4a5535d30244ebc2be84a2080dffb84e5fb868c6
14:51:18 Device Class: iPhone
14:51:18 Build Version: 11D257
14:51:18 Product Type: iPhone3,1
14:51:18 iOS Version: 7.1.2
14:51:18 Obtaining activating data14:51:21 Activating14:51:22 Operations are completed
14:51:22 Elapsed Time: 00:00:04
tanks 3uTools tame

After you try to update or restore your iOS device in iTunes on your Mac or PC, you might see error 53 in iTunes and 'Connect to iTunes' on your device.
Error 53 appears when a device fails a security test. This test was designed to check whether Touch ID works properly before the device leaves the factory, and wasn’t intended to affect customers. This tutorial is for anyone who experienced error 53. You can try the methods below to solve this iTunes error.

# 1. Solve iTunes error 53 using 3uTools
Download and install the latest 3uTools on PC. Connect iDevice to PC using the USB cable. Choose the available firmware for you iDevice and start to flash.
You’re suggested to choose the latest public firmware version for iDevice, because for some beta firmware versions, they are unstable and even exist unknown bugs, your iDevice may be damaged.
#2. Clear out the Junk

Cache files tend to build up, every time you download and install programs or visit websites. These should be cleared out on a regular basis to ensure your PC is running at peak performance and there’s nothing to interfere with iTunes. After clearing your cache, restart your PC, connect back up to iTunes and try again. 3uTools can help easily clean iDevice’s garbage.
#3. Update Windows
This is perhaps the most logical fix. Whenever Microsoft this there is a problem with Windows, it will issue an update so it is vital that you install all of the essential updates on a regular basis. Download and install any that are waiting and then trying iTunes again, to see if the error has been resolved.
#4. Update your PC Drivers
Out of date or corrupted device drivers may be a cause of the iTunes error 53. Ensure that all of your device drivers are fully up to date before trying to update or restore your iPhone through iTunes again.