Fully Tested Unlocked Replacement Mainboard Repair Accessory For Samsung Galaxy Z Flip4 SM-F721U SM-F721B Logic Motherboard

model: with your phone！ Model: For Samsung Galaxy Z Flip4 Z4 F721U F721B ROM: 256GB 1.If you don't know how to install,please do the assembling by the professional person. 2.About buyer updates or upgrades the system, you can update the OS. But only in this way: Use USB cable to contact with the itunes on the computer to update the OS. Never to update the OS system directly with your phone(Because the mobile phone update system is risky, if the update is not correct, the mobile phone will work abnormally).SO Please note,thank you