"Press and hold Press Volume UP + Home Button + Power Key at the same time to boot into Recovery mode."
dle linku "https://devs-lab.com/install-cyanogenmod-13-in-gal axy-s3-i9300.html"

nic na zálohu tam nemám, ani na instalaci

Android system recovery <3e>
Volume up/down to move highlight; power button to select.

- reboot system now
- apply update from ADB
- apply update from external storage
- wipe data/factory reset
- wipe cache partition
- apply update from cache