2016 Focus battery light on.

A few days ago when i started the car the battery light came on then i had driven for around a day or 2 after which the battery was not charging and once connecting a obd scanner it showed these erorrs “lost comunication with starter/generator control module” (code U0120), “Test failed” ( code 0120D),”Running board lamp circuit short battery edge” and a link to some modification website (code B1215). After changing the alternator and doing BMS reset it showed 13.9-14.1V but the battery light did not turn off. After a day or so of driving the battery did not charge again at all and now when i turned on the car when it had charged for a bit the battery drained really fast. Also when i had the car running when using the test menu to check how much voltage the battery had it showed 6V but when i tested with digital multimeter it showed 11V or 12V. I have tested all of the fuses in the fuse box in engine bay and on the side of the battery as well as changed the alternator and tested voltage with and without BMS sensor but it did not have different results when measuring. Anyone has any ides what this could be? I also saw that it could be a fuisible link but i saw someone say that they were only on 2.3L duratec engines but this has a 1.6L engine.