I got this: https://www.ebay.de/itm/274398804823
What can I test? Do I have to set something to power them?
Thanks
Checking the original site for the YouLoop
https://airspy.com/youloop/the "RTL-SDR blog" is listed as one of the sellers and the eBay link you posted should be legit, so ... yes, I think you have the original antenna; as for what to test, if you look at the AirSpy page, you'll see that the YouLoop is a simple, passive loop

so there's nothing to "power" the only thing you could do is pick a multimeter and use it to verify the various connections to see if there's a broken one, as a note the "issue" has been reported by other YouLoop users, the upper "cross connect" box and the lower "balun" box are quite delicate and, twisting the cables and/or the connector may easily break the internal connections, if that's the case then, aside from attempting a repair, the only other option is to return the unit as defective; in such a case you may try contacting the seller (RTL-SDR)
https://www.rtl-sdr.com/ asking for infos and or guidance before returning the item