My PowerMax 55 amper from 2015 has two 40s. Anyway, it is not clear what was blowing your RP fuses. You do need to replace both if just one blows.
Since they are not blowing now, you must have fixed whatever was wrong. No idea what the popping was from but it works now.
If it continues to smell bad after a while instead of the smell going away, I would take the converter out and drill the four corner rivets out that hold the lid on and check under there for what might be covered with black smoke. The lid might have screws instead of rivets depending on when it was made. It will be warm while on and have some normal smell, but the nose knows when the smell is unusual.
You might have lucked out though. :)
