That's what I was thinking about, too. Because of that I have sticked on every Hasboard and on the controller a hologram sticker which rips off when you try to remove it. If he wanted to scam me and to change his defective hasboard with one of mine, he would have to remove this sticker. In addition, I have also noted the serial number.

Yes, I bought it from China. When I received it everything worked, a few months later I sold it to somebody and shipped it. When the buyer received the miner he told me that it's just beeping and not working. Then he returned it to me and I made a firmware downgrade which at least stopped the beeping and made possible to see that only one of the two hash boards where working.

Hello!

I got a problem with my Antminer S5. As you can see in the picture, the Miner is recognizing both hasboards, both got the asic status oooo but only on of them is really hashing. I already tried to clean the contacts, changed the cables connecting the controller to the hasboard, but nothing changed. Well, at least after I cleaned the contact the status changed from ------------ to oooooooo . Do you have any clue what the problem is? It's my first miner and I don't have so much experience with this stuff. Thank you in advance!

Oh and don't wonder : The fan is working just fine but isn't displayed

Screenshot :

https://prnt.sc/gus8ek