Hi @Anonymous ,
Do you want to set the visible and DefaultMode property of the Edit Form through the Button?
Could you please show me the OnSelect property of Button?
I assume you have a List in SP and made a test on my side, please try the following workaround.
I create this list in SP.

Set the OnSelect property of Button1 to following:
Set(VarFormVisible,true);Set(VarFormDefaultMode,FormMode.New)
Set the OnSelect property of Button2 to following:
Set(VarFormVisible,true);Set(VarFormDefaultMode,FormMode.Edit)
Set the Visible property of Form to following:
VarFormVisible
Set the DefaultMode property of Form to following:
VarFormDefaultMode
You will see this.



Best Regards,
Zhi Chen