Question [Q] Steps to get back warranty

Hi, could someone write steps to possible return warranty ?
If I unlock bootloader I loose it, and I read when I flash stock ICS rom is impossible check bootloader status, but what with fastboot and recovery ?
How can I make it invissible in service ? Or if I flash stock ICS rom it will remove recovery ? Because I found recovery.img after extract KDZ...
Thanks for replies
Samsung Galaxy S3 16GB (I9300)

Rom: Stock deodexed
Android: 4.3
Root: Yes
Build: GNA5
Modem: GNA8
Kernel: Boeffla Kernel 5.2
Bootloader: Unlocked
CWM Recovery: PhilZ Touch 6 Recovery v6.40.0 - 6.0.4.8
Memory: ADATA 32 GB class 4

My works: MineBean V20P for LG Optimus L9