DDJ-SB only turns on, won't be recognized by any PC

Yesterday I bought a second-handed SB and it only turns on, does the splash thingy and stays with the "Filter Fade" and the Hot Cue lights on, and when I do the diagnostics, every single button does work. I got the thing to work for about one minute when I disassembled it completely. I have a Macbook 2010 with Mojave and running Djay Pro but also tried Serato with no luck. Tried 3 different cables with 4 different computers (Macbook Pro 2014, Toshiba Core i3, Dell Vostro 1520 and the Macbook 2010). I don't know what's wrong with this thing, cleaned every contact, USB port, and everything. Tested every ribbon cable with a tester and everything was ok. I don't get it. Has anyone got this problem? I got it knowing it wasn't working, I thought it was the USB or something easy to fix but I can't figure out what's the problem here, there is no evidence of water damage. It only cost me 70 bucks so if I can't get it to work it's not that much of a loss.