Apple Service Toolkit is proprietary software available only to Apple Authorized Service Providers and Self-Servicing Accounts. Unauthorized use or distribution is a violation of Apple's terms of service.
The toolkit version number flickered: 1.5.3 (30) became 1.5.3 (31). An update, mid-scan. Impossible. Apple never pushed OTA updates to repair tools. Apple Service Toolkit - 1.5.3 30