I have found another SVGB to SVG converter.
It has a graphical interface using QT library.
I have packed both of them (the converter and de QT library) in a standalone RAR file.
It works fine for all SVGB files, even those that it can be found in the SplashScreen.mif, the initial logo "NOKIA" that appears in first place when your mobile is switched on.

Here you can find the RAR file:

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