If it were me, I would step back and check the basics. A lot of assumptions tossed around already for just starting to troubleshoot.
Please make sure you check some videos to make sure you don't do some damage (I get nervous giving people ideas...), but there are some screws by the MPPT inputs that you can check voltage on with a known good meter. That way you can see if there is actually some solar input getting to the unit, and not some type of other wiring fault. Check all switches and breakers. Possibly a complete power off, and just start with one source.
If you don't take it one step at a time, its just a frantic game of hunting for problems all over the place.
Once you are done with all the connections, carefully check settings one at a time. Things like TOU settings can make a unit not use the battery. In that case you would only see grid pass-through, like you are seeing now.
Slow and steady.