I bought some cheap Arduino Nanos from ebay, but the watchdog does not work in them.
So I removed their old bootloader and burnt a new Nano bootloader from the Arduino IDE. Same problem, the watchdog didn't work.
Then, I burned a Uno bootloader to the Arduino Nano and now the watchdog works properly. The only issue here is that in Arduino IDE I now have to tell it that I am programming an Arduino Uno instead of a Nano. So far everything seems to work just fine.
Are there other problems that may arise from using a Uno bootloader in a Nano? I notice that there are some extra analog pins in Arduino Nano, but I will still be able to use them with the Arduino Uno bootloader right?