i got same avrdude: getsync not in sync 0x0000 kind of error while loading a simple blink led code…b4 few minutes my Arduino Uno Rev 3 board was working nd loading properly….
Now i read all above chats and followed every idea there…i used FLIP to reupload hex by shorting reset nd gnd pins near usb….even after doing that i still get same error…i hva another uno Rev3 board in working condition….so i removed atmega328 ic from problem board nd fixed it in working board….then it loads perfectly…so i dont have problem with bootloader in the 328 ic….i reuploaded atmega16u2 hex file using FLIP successfully…what cud be possible problem??i m not so rich to afford a loss of my money….pls guide me….
Based on your description you already tried this guide https://www.virtuabotix.com/how-to-cure-sudden-uno-death-syndrome/. Since your Arduino Uno worked when you exchanged the ATMEGA chip your Arduino Uno the most likely reason for your problem is that you somehow damaged your ATMEG328 chip.