A new inverter is like $40. It's a quick and relatively cheap troubleshooting attempt. If it works, great. Worth $40.
If it doesn't, well you've got an extra inverter. You'll need it eventually anyway.
But I'd also try the time honored procedure of taking the whole system apart, putting it back together, and seeing what happens. I can't count how many times I've tried to diagnose a problem and missed it, only to fix it unknowingly by taking it apart and putting it back together.
You could have some kind of unnoticeable short in the electrical connections somewhere for all you know. Taking it apart and putting it back together could remove whatever was shorting the system out. Just as an example...