Get openGLwidget linked with Qtimer update

I m trying to build a gui with Pyqt5. and withing the gui there is an openGLwidget, that should contain a rotating cube. But i cannot figure out how to make the cube rotate. Thank you. this is the setup function

def setupUI(self):
    self.openGLWidget.initializeGL()
    self.openGLWidget.resizeGL(651,551)
    self.openGLWidget.paintGL = self.paintGL
    self.rotX=10.0
    self.rotY=0.0
    self.rotZ=0.0
    timer = QTimer(self)
    timer.timeout.connect(self.Update) 
    timer.start(1000)

and here is the paintGL and update functions:

def paintGL(self):
    glClear(GL_COLOR_BUFFER_BIT)
    glColor3f(0,1,0)
    self.Cube()
    gluPerspective(45, 651/551, 1, 100.0)
    glTranslatef(0.0,0.0, -5)
    glRotate(self.rotX, 1.0, 0.0, 0.0)

def Update(self):
    glClear(GL_COLOR_BUFFER_BIT)
    self.rotX+=10
    self.openGLWidget.paintGL = self.paintGL

There are different current matrices, see glMatrixMode. The projection matrix should be set to the current GL_PROJECTION and the model view matrix to GL_MODELVIEW.
The operations which manipulate the current matrix (like gluPerspective, glTranslate, glRotate), do not just set a matrix, they specify a matrix and multiply the current matrix by the new matrix. Thus you have to set the Identity matrix at the begin of every frame, by glLoadIdentity:

def paintGL(self):
    glClear(GL_COLOR_BUFFER_BIT)
    glColor3f(0,1,0)

    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    gluPerspective(45, 651/551, 1, 100.0)

    glMatrixMode(GL_MODELVIEW)
    glLoadIdentity()
    glTranslatef(0, 0, -7)
    glRotate(self.rotX, 1, 0, 0)
    self.Cube()

Invoke update() to update respectively repaint a QOpenGLWidget:

timer = QTimer(self)
timer.timeout.connect(self.Update) 
timer.start(10)

def Update(self):
    self.rotX += 1
    self.openGLWidget.update()