The following factors are to be considered before disassembly and reassembly.
1) Shut down the computer system before the commencement of the process. It is hazardous to perform any such activity with the computer system power on and connected with the power supply. Detach the power cable .
2) Remove all the interfaces of the devices connected with the cabinet(computer system).
3) Perform the task at the dry, non humid area to prevent environmental problem.
4) If you are inexperienced, take a picture of the inside assembly of the cabinet, so that you can attach the right thing at the right place at the time of reassembly.
5) Keep all the screw properly and fix all of them at the appropriate place