My Galaxy s3 failed due to the exynos mem bug while in warranty... The service guy said it was because of water, and out of warranty, but the showroom manager was my friend and he argued with them and made them change the motherboard in warranty...
Also samsung guys messed up and gave the phone to me after registering the new motherboard with imei of another customers phone, and they took it back erased it and wrote an entirely new imei for the phone...
I probably would ve been screwed if not for the manager.