Program previously loaded doesn't load on boot

Hello, I bought an arduino uno some time ago, and with time and accumulation of errors I started to burn some I/O pins, so I bought a new arduino uno chip and replaced it on the board.

The problem now is when my arduino boots, ie, I plug it into the usb and the led on pin 13 starts flashing many times like this ... ... ... and it doesn't stop. If I turn the serial monitor on (even without any serial communication programmed) the program I previously uploaded into the arduino starts normally. Just to be sure I wrote a code that brings all pins to HIGH just to test and the led on pin 13 only stops blinking when I turn the serial monitor on or upload the program again. The chip comes with a sticker that says ATMEGA328 UNO BL. I don't know if this details are enough, but if something else is needed just ask.

Thank you.

Hey guys, I'm bumping the thread to see if more people watch this problem, I'd be very happy if someone could give me directions.

So I read the trouble shooting guide:

Why doesn't my sketch start when I'm powering the board with an external power supply? (Arduino Diecimila or earlier) Because the RX pin is unconnected, the bootloader on the board may be seeing garbage data coming in, meaning that it never times out and starts your sketch. Try tying the RX pin to ground with a 10K resistor (or connecting RX directly to the TX pin).

Why doesn't my sketch start when I power up or reset the Arduino board? Most likely because you are sending serial data to the board when it firsts turns on. During the first few seconds, the bootloader (a program pre-burned onto the chip on the board) listens for the computer to send it a new sketch to be uploaded to the board. After a few seconds without communication, the bootloader will time out and start the sketch that's already on the board. If you continue to send data to the bootloader, it will never time out and your sketch will never start. You'll either need to find a way to stop serial data from arriving for the first few seconds when the board powers (e.g. by enabling the chip that sends the data from within your setup() function) or burn your sketch onto the board with an external programmer, replacing the bootloader.

I think it's one of these... because I just now used a battery to power the arduino (I was using USB) and everything went ok. In he previous chip all is ok. I ordered two atmega328 uno bl and both of them have the same problem.

Thank you.

I came here just to tell anyone with the same problem as me that your problem is probably the chips you bought came with a different bootloader then the original arduino that we buy together with a board.

All I did was read about how to burn a bootloader and do that in each of the two chips that had this problem.

All is good now, if someone has trouble burning bootloaders tell me, maybe I can help =).

Thank you anyway guys.