Guarantee vs. Warranty
After installing a new component into your computer don’t believe the technician if he wants to tell you that you cannot reclaim a defect anymore. You bought yourself an extra hard disk for your new computer. Before opening the case, you saw that it was sealed. The seal read that you would loose any guarantee upon breaking the seal. Disregarding this warning, while opening the case, you broke the seal. Later after noticing a defect on the sound card, you returned this apparatus to the vendor only to learn that he will not repair it under guarantee rules because you broke the seal. Can this be?
Yes, this can be and it is legal. However, you have to strictly distinguish between guarantee and warranty! “Warranty” is legalese and means the producer’s or service provider’s legal liability to compensate you for any defects that are his fault. “Guarantee” is the producer’s contractual promise to be liable for defects beyond any statutory warranty period. The producer can stipulate conditions to this guarantee, as he has no statutory obligation, which lays down any rules for liability. Such a condition may be that you do not break his seal. Following §438 BGB you have two years time to reclaim defects of your bought item. During the first six months, law assumes that the damage has already occurred at the time of sale. What does this assumption tell you? This is a procedural evidence rule laying the burden of proof on the vendor to prove that the product was without defects at time of handing it over to the customer.
However, your technician is wrong. It can be that you have lost the guarantee but this has nothing to do with the statutory warranty found in the civil code. If the sound card really has a defect that you did not cause, then the vendor is legally obliged to repair every defect he has caused – be there a seal or not.
What about the external hard disk you recently bought online for home? You are saying you returned it within the given two weeks but now the vendor wants to have € 15 because you did not return the original box and the disk has a couple of awful scratches. Well, start preparing a transferal. The vendor is totally correct. You are without question entitled to test the disk by opening the package but this was supposed to have been done gently. The vendor has the right to receive the disk returned as if it had not been tested. Since he received the item returned somewhat damaged, he is entitled to damages.
In another store, you bought a graphic card that does not want to work in your machine. The salesman is refusing to take it back because it “works”. To prove that this defect is a case of warrant will not be easy, because it seems that you have a non-compatible component in your computer. Install it in other computers to see if works there. If not, make screenshots or at least have a witness follow your installation to verify that the graphic card does not work. Only until you can show that it does not work in two or even better three different machines, you will have a chance to effectively show that this card really has a defect.