Learn to re-claim a blown Arduino, for a few dollars. Not a fix for all problems you might encounter, but it's a cheap way to troubleshoot your microcontroller.
When I first started working with microcontroller
This project will show you how to remove and replace the Arduino "brain" (ATmega328P uC). And we will re-flash your shiny new replacement chip with the glorious Arduino firmware. One thing to note, however: this project will only fix your Arduino if your Atmega328P controller is blown. If any other component is bad on your Arduino then this guide will more than likely not be helpful. With that said, let’s fix an Arduino!