You have never mentioned which model of Kindle Paperwhite you have.
It makes a difference.
Use the device's first four (or first six) characters of its serial number and this table:
https://wiki.mobileread.com/wiki/Kindle_Serial_Numbers
to identify your model.
You have never mentioned what serial-to-usb adapter you are using.
It makes a difference.
Please post those details so that we do not give you the wrong directions.
Remember, we can not see over your shoulder.
You MUST give us details.