imma just cut straight to the chase, i used to be able to scan my car with my Foxwell scanner but out of nowhere it just stopped connecting, at first I thought it was just a faulty update so I tried it with another OBD2 scanner which is older and more basic. power works and it lights up but it just says no codes detected (I have a misfire so I know that's a lie) if you unplug and replug enough it'll connect using kwp2000 protocol and it'll show my misfire. ECU has been changed before could that be the problem?

how can I even diagnose what's wrong? and my biggest question is how did this even happen out of nowhere?