accidentally connected 12V to 5V

:frowning: i have accidentally connected 12V to 5V and GND to my arduino UNO ...
now when i connect uno to my pc .system will detect Arduino in serial port with no problem but when i try to upload sketch it will stuck on uploading.

can i get back my UNO to life with changing Atmega328 ??

Arduino: 1.6.5 (Windows 7), Board: “Arduino/Genuino Uno”

Sketch uses 450 bytes (1%) of program storage space. Maximum is 32,256 bytes.

Global variables use 9 bytes (0%) of dynamic memory, leaving 2,039 bytes for local variables. Maximum is 2,048 bytes.

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x45

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x45

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x45

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x45

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x45

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x45

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x45

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x45

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x45

Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

avrdude: stk500_recv(): programmer is not responding

avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x45

This report would have more information with
“Show verbose output during compilation”
enabled in File > Preferences.

Do loopback test.

Also, while the board is plugged in, feel the part in the SOIC-8 package near the DC power jack, and see if it's getting warm. That sometimes gets damaged when you do mean things to the power, and fails shorted, so it gets hot and draws enough current that other parts of the board don't work right.

If that passes, replacing the '328p should work.

Measure the voltage on the power pins (3v3, 5v ).

What if any led's are lit/blinking?

Is it still running the last script that you successfully uploaded?

5V is 4.98 VOLT <<>> :frowning:
3.3V is 3.27 VOLT

no . last sketch is not running
Time of connecting 12V to 5V was lower than 5 Sec
im not sure if the board is dead or just Atmega328 (or both chips)
the blinking is when i press reset button and it will blink for 3 times (like always)
No - non of component are warm … everything looks normal … :frowning:

NOTE : “ON” and “L” led are HIGH

It is hard to know.
If I could afford it, I would order another UNO, and a Atmega328 .

Do loopback test!

If loopback test fails, the USB interface chip is malfunctioning, and that's not practical to replace.

If the loopback test passes, you'll be good if you replace the chip.

However - I have a bad feeling that the '328p is still good, while the usb interface chip is not. That triple-blink indicates that the bootloader is running...

everything is ok until lvl "8" :frowning:

there is no difference between this mode(loopback test) and normal connection

windows will detect serial device as soon as i connect Arduino to PC