SAOCOM data Terrain Flattening

Hello,
I am trying to apply the Terraing Flattening operator to some SAOCOM L1A images.
To do so, I need to have a beta0 band. As SAOCOM scenes should be already calibrated I do not want to perform the calibration step. Also, it creates wide white border outside the image (with hight dB values).

I tryed to calulate beta0 it using band math and the calibration factor (in the ConfFile, called ) with:

0.96*pow(Intensity_VV,2)

Is it correct? The Terrain Flattening operator still not recognize it as a beta0 band.
As a different option, I tryed to perform the Radiometric Normalization when applying the Terrain Correction, to obtain gamma0, but it seems to make it worst (using the ellipsoid angle and also DEM angles).

Any ideas?
Thank you