Low battery or dirty contacts.
Because these units are often rebranded by different industrial suppliers, you can find official documentation through: Zy-8068 Manual Pdf
If you have downloaded the PDF, locate the "Calibration" section (usually page 12-15). Most Zy-8068 devices follow a standard calibration routine: Low battery or dirty contacts
: Includes power failure protection to retain data and optional password settings to prevent unauthorized parameter changes. Troubleshooting & Wiring Malfunction Prevention Zy-8068 Manual Pdf