1.Turn off your HP 15-ac121nj laptop, disconnect the AC power cord and remove the battery cover and remove the battery.

2.Turn a laptop, from the bottom of the laptop disassembly screws, refer to your laptop's user manual position, and set them aside.

3.Remove the external components, including memory modules, wireless LAN and modem

4.Remove the keyboard assembly of all the screws, gently lift the keyboard assembly from the bottom, remove the keyboard. Unplug all cables and various internal components.

5.Disconnect any wires to the HP 15-ac121nj motherboard. Unplug any cards, such as the video card, not directly built into the motherboard. You will have the opportunity to remove the motherboard screws, disconnect the cable to the power strip.

6.Remove the CPU, the CPU into a new HP 15-ac121nj motherboard, re-assemble parts in reverse order.