You have to reassign the output of a module to a variable.
Your current code doesn’t use the output:
        self.dw_conv2(x)
        self.batch2(x)
        self.PRelu2(x)
        self.conv3(x)
        self.batch3(x)

and it should be changed to:
        x = self.dw_conv2(x)
        x = self.batch2(x)
        x = self.PRelu2(x)
        x = self.conv3(x)
        x = self.batch3(x)