DIAGNOSIS A firmware corruption or major internal fault. Error 30 requires a full factory reset.
FIX Perform a hard reset. Pull the thermostat off its wall plate. Remove one of the system wires (e.g., the R wire) for 30 seconds. Reinsert the wire. The thermostat will reboot. If the error persists, initiate a factory reset: Hold the Fan and ^ (Up) buttons for 5 seconds until the screen clears. You will need to reprogram all settings.
IF THAT DIDN'T WORK The unit may have a defective main processor board. If the hard and factory resets do not clear Error 30, the thermostat itself needs replacement.
HEADS UP A factory reset erases all schedules, Wi-Fi settings, and custom configurations. Have your system setup details (like heat pump type) handy to reprogram it.