Peter,
Have you tried replacing the batteries in the meter? I’m not sure about OAD specifically, but some folks have had problems with firmware updates if the meter batteries were low.

Although it sounds like you have tried a few things, here is a list of the easy steps to try based on various posts from James and others in this forum.

1. In the phone, turn airplane mode off then on. Sometimes that is enough.
2. Reboot the phone. Sometmes 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.
8. Try a different phone if possible. Pre-paid phones with android 4.4 or 5 can be obtained on sale for $20 or less (in the USA) and they don’t have to be activated, just use wifi. A dedicated phone for this also frees up your main phone.

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