I want to hand over a laptop under warranty, but I want to make it prepared

Hi, habracheloveki. Periodically, posts on someone's bitter experience of handing over their laptops / phones appear in Habré, in which the authors talk about their adventures in repair shops and stores. Then, legally savvy and experienced in this regard, habracheloveki leave in the comments their thoughts about what the topstarter did right and what did not.
So, I have a need to carry a laptop under warranty repair, which has stopped working DVD-ROM. The laptop is still on the official warranty store "Eldorado" (Ukraine, Dnepropetrovsk). How can I properly repair it? What documents do I have to fill in, what do I need to get in my hands, should they be given by another laptop, etc., during the repair period? Any advice would be welcome. Thank you in advance!
ZY Separate hello to the trolls, who have nothing to say and they poke on the minus button)