If you go 3rd party shops to repair, it is considered as modification, so if next time you want to go repair at Samsung, they will ask you to change the whole thing.
Just like my Note5, when it cannot power on, Samsung say motherboard spoil, and it costs about $460+ to repair. so I go 3rd party shops to repair, they only charge me $190+. after that went back to Samsung to change the back cover, they did a check and found out that my motherboard is modified, so they ask me to change everything which costs $460+. I say I don't want then they proceed to change the back cover, and of course during the process of changing, if anything goes wrong, they are not responsible for it.