The BLE SENSE, BLE, and 33IOT have TWO COM ports.
The second COM port also often referred to as "BOOTLOADER" can be invoked by quickly double tapping the reset button.
It can also be used to help clear out a sketch that does not behave. For that simply put it into BOOTLOADER mode then upload either BLINK or BARE MINIMUM from the EXAMPLES.
The IDE knows and expects this type of action and can handle it.
Most often there is no need to chase the new COM port or to force your OS to choose another port as this can lead to further issues.
However there have been some scenarios with other boards of this nature where over aggressive antivirus, Cloud / network or portable based IDE installs can cause delays which result in some problems.
If yours is one of those types of problem then unless you have some decent knowledge of networking etc.
it is often best to uninstall the IDE and re-install to a local drive.
If you think it is antivirus / security based then you need to add the install locations to your whitelist / exclusions.
Each security program is different so no quick answer for that.
Another is USB 3.x issues. There are well known not just for Arduino but other USB peripherals too.
It can be your computers CHIPSET that may not be fully compliant. The most common fix is to insert a USB 2.0 hub between the Arduino (or errant peripheral ). This acts as a buffer in most cases
Last but not least are USB driver issues under Windows. If your USB drivers were supplied by Microsoft you should consider going to the hardware manufacturer site and getting the proper drivers as microsoft has a habit of breaking some of the drivers. This extends beyond USB with the second largest problem being Graphics card drivers supplied by microsoft.
Please rule all those aspects out first.
NEW NANOS GENERAL.
AVOID using libraries not specifically for the new NANO boards unless you are conversant with making any needed changes to the library. Instead most examples are included when you install the core files for the board.
If you cannot find a library for your new NANO then start by using the LIBRARY MANAGER from the IDE.
The keywords you need to use to whittle down the ones you want are "nano", "sense", "iot", "ble" but be sure you pick the ones from ARDUINO.
Also including a pdf that may help with some of those aspects (but not all)
- Ensure you turn off any additional security / antivirus just to test.
- Where possible use USB 2.0 ports or a USB 2.0 POWERED HUB.
- Try other computers where possible.
- Try other USB leads where possible.
- Avoid cloud based installations where possible OR Ensure your cloud based software is RUNNING.
- Boards that use a MICRO USB plug should be both CHARGE and DATA. Many are CHARGE ONLY
Open the IDE. Select TOOLS.
Select Board the Board Manager.
When the box opens up wait until it has downloaded any new or updated items.
Then in the blank box type the board you wish to install.
You do not always need the full name.
Select the correct variation and click the INSTALL option.
Please be patient and wait until it has finished.
Although not needed I often RESTART the IDE at this point.