Oops. ?
I apologize for my ramblings.
I didn't see the error you were talking about (upper left corner) when I viewed the post from my phone.
Is the firmware up to date on the Spark and / or
batteries?
If you purchased a new
battery, it may need updated, but the app should tell you that.
You might try reinstalling the Go4 app. It couldn't hurt.
I'll dig around a little more to see what I can find but it's time to walk the dogs.
Here's the Goggle search results for
Battery signal error dji Spark to get started.