Tensorflow Model fitting ValueError: Layer sequential expects 1 inputs, but it received 520 input tensors
First of all look at the shape of tensors that your tf.data.Dataset returns then try to set the input_shape of the first Dense layer like:
model = keras.Sequential([
    layers.Dense(520, activation='relu', input_shape=(1, 519)),
    layers.Dense(520, activation='relu'),
    layers.Dense(520, activation='relu'),
    layers.Dense(1)
  ])

or explicitly add the Input layer
or set the number of neurons of the first Dense layer corresponding to the number of features (519)
Also read the docs they are really great:
https://www.tensorflow.org/api_docs/python/tf/keras/Sequential