Arduino File Upload Error

I have two arduino UNO board, but I rarely use those two, only one. Today, I needed to use the one that was stored and it is not uploading the code. The load takes about one or two minutes and gives an error: stk500_getsync() attempt 10 of 10: not in sync: resp=0x02

where this "resp" value changes everytime i try to load.

I noted to that when I try to send something with Serial, the RX led does't blink.

My other Arduino is working perfect.

Help me please ;-;

Rebootload the '328P and start fresh. Check that the Loopback test (top of this forum) runs to ensure the 16U2 is working.

CrossRoads: Rebootload the '328P and start fresh. Check that the Loopback test (top of this forum) runs to ensure the 16U2 is working.

I didn't pass in the test. I also tried to switch the 328 but nothing happens.

And I can't put the Arduino in DFU mode, nothing happens when I short the pins