Here is a summary of the easy stuff you might try based on various posts from James in this forum.
1. In the phone, turn airplane mode off then on. Sometimes that is enough.
2. Reboot the phone. Sometimes that is enough.
3. In the phone, go to Settings->Bluetooth->Paired Devices. If the Mooshimeter is listed under paired devices, delete it.
4. Open the case (2 screws) and press the tiny reset button (near the microSD card slot). This reboots the meter.
5. Remove the 2 batteries and check their voltage with another meter and replace if low. Some people have had low/dead batteries even if they haven’t used the meter much.
6. Sometimes the meter thinks it is still in shipping mode, so momentarily short the meter probes between ohm and common.
7. Uninstall and reinstall the Mooshimeter app.

Hope one of these helps your meter.
— – – – Duane