Judging by iTunes error codes and their corresponding analysis, the fault might be caused by damage of the NAND flash chip or malfunction of NAND relevant circuits. Let’s start with measurement of the power supply of NAND. Connect battery connector with the DC Power Supply. Get the motherboard powered on with tweezers.

Run voltage measurement of the power supply of NAND. The measured value (0.9V, 1.8V and 3.0V) is normal.

Let’s replace with a new NAND flash chip and see how it works. Place the motherboard on the specialized Heating Platform. Remove the sponge covering the board first. Power on the heating platform and set the temperature at 155℃.