As concerns, the TensorBoard analysis, from the folder where the source has been executed, you should digit:
$> Tensorboard --logdir = 'log_simple_stats_5_layers_relu_softmax'
Then open the browser at localhost to visualize TensorBoard's starting page.
In the following figure, we show the trend's accuracy over the number of examples of the training set:
Accuracy function over train set
You can easily see how the accuracy, after a bad initial trend, begins a rapid progressive improvement after about 1000 examples.