Question about Petkit Eversweet drinking fountain, 1.35l

Good evening, I ordered this fountain and after installing it following the instructions to the letter, the filter light came on, I tried to replace it and reset it but nothing happened, it is still on and the fountain does not work. I have tried to replace it and reset it but nothing works, it is still on and the fountain doesn't work, so I was exchanged and again the same problem. I have read the instructions over and over again and I can't see where my fault lies. Can anyone think of a solution? Thank you in advance!