Arduino UNO not working? Recently I assembled my Shapeoko machine, we used Grbl shield with an Uno for the same.

For 1-2 weeks everything worked perfectly then once when I tried to work the machine, the serial communication was not working. I tried to replace the 16 MHz oscillator because I thought the problem might be with the oscillator since the LEDs were not blinking but they were lighting up.
Maybe the 5v regulator? Hard to say without the symptoms.