I’m thinking about the Maslow board with the heat sinks which plugs into the top of the arduino. Taking it off shouldn’t matter, but it does eliminate one more variable.
It could be one of many different things. The problem is either on the computer side or the Arduino side. Arduino failures are rare, but they do happen. If you can try on multiple computers and see the same issue then it is probably an issue with the arduino. On the computer side the issue is usually with some sort of driver. Without the drivers working properly the computer won’t be able to connect to the arduino. If you try the arduino on a different computer and it works then you know it is a drivers thing.
One of the great things about arduinos is that there are a TON of resources online which can help you track down what is going on.
This youtube video seems like it might help: