[PYQT5] Crashing when using .hide() and .show()

[aking76]

My program opens a main window with an investigation button, once that is clicked a second window opens and the first one is hidden.
The second window has a button and when it is clicked it is suppose to hide, however, it crashes.
If I run the second window by itself, not going through the first window, I can click the button and that window will hide. So I'm not sure why they're not working together.
Test.py

 from PyQt5 import QtCore, QtGui, QtWidgets
from Test2 import *

class Ui_MainWindow(object):
    def ipDombtn(self):
        self.window=QtWidgets.QMainWindow()
        self.ui=Ui_MainWindow1()
        self.ui.setup(self.window)
        self.window.show()


    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(412, 440)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.verticalLayout = QtWidgets.QVBoxLayout(self.centralwidget)
        self.verticalLayout.setObjectName("verticalLayout")



        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setObjectName("pushButton")
        self.verticalLayout.addWidget(self.pushButton)
        self.pushButton.clicked.connect(self.ipDombtn)


        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 412, 31))
        self.menubar.setObjectName("menubar")

        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)


        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)


    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Investigation"))


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())  

Test2.py

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow1(object):

    def exIpDomInv_clicked(self):
        print("You clicked a button...")





    def setup(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(412, 440)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.verticalLayout = QtWidgets.QVBoxLayout(self.centralwidget)
        self.verticalLayout.setObjectName("verticalLayout")


        self.exIpDomInv = QtWidgets.QPushButton(self.centralwidget)
        self.exIpDomInv.setObjectName("exIpDomInv")
        self.verticalLayout.addWidget(self.exIpDomInv)


        MainWindow.setCentralWidget(self.centralwidget)
        self.Menu = QtWidgets.QMenuBar(MainWindow)
        self.Menu.setGeometry(QtCore.QRect(0, 0, 412, 31))
        self.Menu.setObjectName("Menu")

        MainWindow.setMenuBar(self.Menu)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")

        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

        self.exIpDomInv.clicked.connect(self.exIpDomInv_clicked)



    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "Investigation"))
        MainWindow.setAccessibleName(_translate("MainWindow", "InvestigationMenu"))
        self.exIpDomInv.setText(_translate("MainWindow", "External IP/ Domain Investigation"))



if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow1 = QtWidgets.QMainWindow()
    ui2 = Ui_MainWindow1()
    ui2.setup(MainWindow1)
    MainWindow1.show()
    sys.exit(app.exec_())