How can I tell whether a failure is hardware, software, or the product?

Run self-test, run calibration verification when accuracy is in question, verify NETS and firmware versions, confirm analyzer and switching configuration, check ACT mappings and addresses, inspect adapters and fixtures, test a known-good product when available, use Connector Test and fault analysis, review the System Event Log, and save the test script, ACT file, results log, and error details for Customer Service.