Tried again the battery trick with the amp completely disconnected, not a single thing changed... Looked in the boot spare wheel well and I can't see ANY connector in there, just a rubber grommet and a cable bundle going through it kind of on the left outer car part of the well, also, no signs of water in there. Also, pulled the cover away from the right side of the boot, and noticed that there are 2 connector that are not connected to anything, one blue and one red, they have the same shape as the 2 that go into the sat nav unit, those are also there and connected to the sat nav, one blue and one pink, but I never touched them before and the seats were also working properly so I don't think it has something to do with that.
I looked again at all points where I ran the cables for the amp when installing it, all looks clean to me so I'm kinda standing here clueless and it's really annoying
EDIT: Looked a little bit deeper into the RAVE CD for the memory seats system description and figured out some things, the communication between the 3 memory push buttons and the seat memory ECU is intact, because 1st: it can store new memory positions, and 2nd: did a seat memory self test mode and that also confirmed that the buttons are communicating with the ECU. Now, the problem is, as far as I can see, the ECU receives the command from one of the 3 push buttons when they are pushed, but somehow, doesn't send it forward to the motors, also, if a relay inside the ECU would be faulty, it says that it would show on diagnostics, and I am pretty sure that either my Toaf or Delphi would've picked them up. Another thing that I don't know, is that the ECU communicates with the BCU also, but doesn't state for what, my guess is that only for the lazy seats part of the system, because the memory seat positions are stored in the seat memory ECU, and also, regarding the K bus, how can I know if that really is the issue for my problem? Can I measure the K bus wire somehow and tell if it works by measuring it's voltage for example? And also, what is the role of the K bus wire for the memory seats in my case and what would happen if it wouldn't work properly?