IPhone 12 Stuck on the Apple Logo Error 4013 Repair

IPhone 12 Stuck on the Apple Logo Error 4013 Repair
Device	IPhone 12, IPhone 12 Pro, IPhone 12 Pro Max, IPhone 12 Mini
Affects part(s)	Motherboard
Needs equipment	screwdrivers, spudger
Difficulty	◉◌◌◌ Easy
Type	Part replacement

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Problem description

Diagnosis and repair of an iPhone 12 that boot loops and only shows the Apple logo on screen.

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Symptoms

• Shows Apple logo for about 5 seconds, then blank, then Apple logo, then blank.
• Sometimes it shows a green flash for a second.
• If you try to flash an update or restore, it fails right away with an Error 4013.
• If you flash on 3U Tools, it fails at 19%.

Solution

Flex Cables:

• Step 1 in this case is always unplug all the flex cables.
• Ideally test the board with known good screen, battery & charging port.
• If it boots, then one of your flexes is the cause.
  • 99% of the time, it is the ear speaker flex. The flood illuminator and/or the ALS has liquid damage.
  • The ear speaker flex is paired to the logic board for Face ID.
  • If you want to keep Face ID, you'll need to repair the flex. If Face ID is not important, then you can just replace the flex.
    • To repair the flex, you'll have to desolder the component & clean out all the corrosion, then place them back.
    • If the corrosion is too severe & it damaged the flex, then you'll need to swap the flood illuminator and ALS to a new flex, otherwise, you'll lose Face ID.
  • In some cases, another flex can cause this issue like a bad charging port.
    • In this case, just replace the flex

Please Note: If the phone is stuck in Recovery Mode because it failed at the Error 4013, you have 2 options

1. Kick the device out of Recovery Mode using 3U Tools. In the main screen of 3U Tools, you'll see a button that says "Exit Recovery Mode"
2. You can attempt another update or restore.