I had No Joy using the USB for updating / correcting the firmware on my H3 GMRS...
Rookie mistake upon my part by selecting the incorrect radio on the OdMaster App. It overwrote to the incorrect version.... Limiting it to 1 channel only. Again, a noob error.
I know old news, but the PTT + * keys 'secret menu' saved me.
Now only if they'd develop an OTA firmware update.