Samsung implements a rollback prevention (bit) system. You can upgrade to a higher binary version, but you cannot downgrade to a lower one. Trusted Download Sources
Installing firmware on a G900F requires a PC and a tool called . skachat proshivku g900f
Avoid sketchy third-party forums. Use these reputable platforms: Samsung implements a rollback prevention (bit) system
Power off the phone, then hold Volume Down + Home + Power simultaneously. Confirm with Volume Up. skachat proshivku g900f
Step-by-step instructions for before you flash. Which of these would be most helpful for your project?