Reviving an iPad 2018: CPU Reballing Step-by-Step

Introduction:
- Brief overview of the problem (iPad 2018 not booting up)
- Explanation of the diagnosis (faulty CPU connection)
- Outline of the solution (CPU reballing)

Tools and Materials:
- Micro-soldering station
- BGA rework station
- Lead-free solder balls
- Flux
- Precision tweezers
- Thermal camera (for diagnostics)

Process Breakdown:
1. Disassembling the iPad: Carefully opening the iPad, disconnecting the battery, and removing the logic board.

2. Diagnosing the Issue: Using a thermal camera to identify heat irregularities around the CPU, confirming the need for reballing.

3. Preparing the CPU: Gently removing the CPU from the board using the BGA rework station, ensuring not to damage any nearby components.

4. Cleaning and Flux Application: Cleaning the old solder off the CPU and the board with a solder wick and applying flux for the new solder.

5. Reballing Process:
- Placing the CPU in a reballing stencil.
- Positioning lead-free solder balls onto the stencil.
- Using the rework station to melt the balls and form perfect solder joints.

6. Re-attaching the CPU: Carefully aligning and soldering the CPU back onto the board.

7. Testing and Reassembly: Reconnecting the battery and testing the iPad before fully reassembling.