Hi,
I have to admit, so far I have almost zero experience with the Arduino. But I use it for my Reprap 3D printer, where its hooked it up with a shield, which among others carriers Pololu A4988 motor drivers.
Recently, I fried two of those motor drivers and now I am drying to find the root cause.
As mentioned with actually zero Arduino experiences, I was thinking "how can I check if my Arduino Mega2560 is broken?". What I did: I found a sketch called "Blink", which I applied to all pins from 0 to 53. Interestingly, while for all pins the LED blinked as expected, pin 30 behaved differently: at pin 30 the LED is ALWAYS on, even after sending a "digitalWrite(30, LOW)".
Additionally I tested the AnalogIn-Pins with an example sketch "AnalogReadSerial" and a potentionemter: all AnalogIn Pins behaved as expected (by turning the poti, the numbers on the SerialMontior changed accordingly).
I am wondering: is this for me strange behavior of Pin30 really a reliable indicator that the Arduino is really broken and I have to throw it away?