12v Power with Arduino Test

Tonight I tried to get my Arduino to work stand-alone with a 12v, 2A external power supply.  I hooked the Arduino up to my servo motor, then plugged it in to power.  It worked as I expected it to.  The Arduino made the motor spin one direction for 1 second, then the other direction for 2 seconds.  It stopped after one minute.

Next, I wanted to connect the servo to a fixture I had 3D printed for the automated dog food dispenser.  It
took me several minutes to get the servo connected to the fixture.  The Arduino was plugged in to the 12v power the whole time.  When I was ready to test the program again, I smelled a slight electrical burning.  I sniffed the servo and the Arduino but neither had a strong burning smell.  The main chip on the Arduino was a bit hot so I unplugged it from the power.

Then, I connected the servo to the Arduino and plugged in the 12v power supply.  The servo did not turn at all and one of the lights on the Arduino that normally turns on did not.

I plugged in the 9v power supply to the Arduino and the servo spun but only in one direction.  Also, it never stopped spinning.  I pulled the wire from the signal pin on the servo and it still kept spinning.  Pushing the reset button on the Arduino also does nothing.

Something is wrong, but I am not sure exactly what.  Maybe I burned out the Arduino chip.  Maybe I just wiped out the sketch from the Arduino.  I have to do more experimenting some other day.

BTW, according to this official Arduino page, the power input range is recommended to be from 7-12v but will handle from 6-20v.  So, my 12v power supply should not have burned it out.