The retailer that sold me the S17+ offered me to send in the defective Hashboard and get a (used but working) Hashboard as replacement.
I think I will try this. Even though I am unsure about potential issues when replacing a Hashboard with another one.
You should accept the offer, the retailer can't send you a worse hashboard than the one you have unless if it doesn't work at all, the problem with your hashboard is very hard to fix, it isn't a matter of replacing a wire or a fan, you will need to locate the bad chip/s, remove them and then re-solder them on the board.
That might seem like an easy thing to do but it isn't, if you are lucky, putting some pressure on each of the heatsinks will be enough to take the bad chip off the hashboard (the bad chips on all the 17 series aren't exactly burned, they just have terrible connectivity due to cheap/bad solder paste) but that only solves half of the problem, the other half would be re-soldering that chip/heatsink back, and that is nowhere near easy and require a good level of skill and a set of tools.
In many cases, the heatsink/chip is indeed loose but not loose enough to fall under pressure, so you will need a fixture tool like this
one just to know what chip/chips which need removing, and that tool isn't cheap by any means, knowing the bad chip/heat sink isn't the end, it's only the beginning, you will need a heat gun to remove it, a bit too much of heating and you could damage the board itself or make another good chip/heatsink lose contact to the board and thus create even more problems.
As long as the chip/heatsink hasn't completely fallen, then it all depends on your luck, it could run for a week then drop for a day then come back, it could do just fine for a few months, it could fall next week and never work again, so getting a replacement is the BEST option you have.