I get the message “Excel could not open toolsforfba_amazon_fba_sales.xlsb because some content is unreadable…”

This is because the spreadsheet is using styles that you may not have or there is something else that you version of Excel does not recognize.

Choose “Open and Repair”

If the entire spreadsheet is does not have any formatting and you use Excel for Mac, please make sure that there are no conflicting fonts in Font Book.