It looks like you are assigning your buttonPress variable incorrectly in bool buttonPress = 'ButtonA.PushbuttonBase::()'. If you want to check if the button is pressed, use the method isPressed(). For example, ButtonA.isPressed(). Also, the ( at the end of if (buttonPress) ( should be {.
If you are still having problems, can you turn on verbose output in the Arduino IDE and post the output that you get at the bottom of the IDE after trying to upload your sketch? You can turn on verbose output by selecting Preferences from the File menu in the Arduino IDE, and then checking the “compilation” and “upload” boxes next to “Show verbose output during:”.