First of all, the hard disk (NAND), which is used and deformed over time, tries to give an error after a while and warn the user by displaying error codes. These codes are error codes such as 09, 40, 13. In such a case, NAND replacement should be done. A second reason is that the capacity is not enough. Because each installed application fills a certain capacity. Before that, even the phone's own files take up a few Giga Bytes of space. This creates a need for memory upgrade. Now let's explain how this memory upgrade and NAND replacement is done.