MEGA2560 bliking led L 2 times and not working anymore, help please

Hello,
I've been searching and couldnt find a solution to my problem. I want to ask for some help because I need my controller working to present a project this week =/.

That's the history: I've connected it to my usb port just as usually and it failed to upload my code. Just this. Now When I turn it on, on the USB, it keeps blinking the L led 2 times in minimal intervals and are not recognized as a COM to be programmed anymore.
Searching around I found that I would need to burn the bootloader again. As I need 2 arduinos for my project I burned it using the other arduino as an ISP, but the problem persists.
I would really appreciate some help in solving this.
Thanks! :frowning:

and are not recognized as a COM to be programmed anymore.

Burning a new bootloader into the 2560 will not fix this problem. You have something wrong with the USB serial interface chip if the computer doesn't recognize a connection.

Lefty

Do you have any sugestion for me?
Is it possible that the comunication chip has been damaged only because my programing process failed? In case of afirmative is it possible to replace it?
Thanks

What is the power led doing?

Hello James, thanks for repplying.
The power LED Is ON all time. the L LED, that one that blinks when you power on the device because of the bootloader is blinking twice a second. I am sure that it must be something like an error code but I couldn't find what this means. Do you have an idea?
Thanks

RogersR:
I am sure that it must be something like an error code but I couldn't find what this means. Do you have an idea?

Well since the bootloader flashes the LED at start, I'm not sure I would call that an error.

The point is that when my mega was working fine, it used to turn that led on but it became off in a few seconds when arduino was ready to work. Now it keeps blinking twice a second forever. It wont stop anymore.

Well the bootloader doesn't flash to indicate any kind of error. So either something is causing the bootloader to reset constantly or you wrote your code in a way to cause it flash.

What was the last code you loaded and what hardware is/was connected?

The last code I wrote was a simple one that would receive a number from the serial usb connected to the computer and would change whe bright of a LED. So just the LED was connected. The code had nothing with the built in LED. :frowning:
Thanks

RogersR:
Searching around I found that I would need to burn the bootloader again.

Where did you read that?

What is connected to the problem board, when it refuses to be programmed?

What did you have connected before (when it worked)? Motors? LEDs?

Hello Nick, Thanks for Answering!
I searched on google and wont remember exactly where I read that, but what I read was that if a uploading process fails it has a chance of corrupting something. As I am totally new to Arduino, I believed and burned a new bootloader into it, using another arduino board, but unfortunatelly it didnt worked. (I mean, the bootloader burning process was a sucess. but the problem stills there.)

I have nothing connected to the problem board, just the USB cable that goes to my laptop.
I have already worked with servos and LEDs on this board.
I'll be waiting for some help. Thank you

While you do not have hardware connected now, it sounds like something you had connected before might have damaged the board.

Hi James,
The only thing connected with the board when it stopped worked was the USB cable.
I've just made this test http://arduino.cc/forum/index.php/topic,73748.0.html and nothing happened. No COM ports and no sound. Just the power LED is on.

... I need my controller working ...

What controller was this? What did you have hooked up, while it was still working?

It is an Arduino MEGA2560 (Atmega2560-16AU).
While it was still working it was receiving a number from the serial monitor and changing the brightness of a LED, from 0 to 255. Just the LED with 1k resistor connected and the USB cable. It stopped working when I tried to update the code with some more Serial.prints
Thanks

Hi, assuming that reburning the bootloader did work, and considering that your first priority is to have the Arduino working ASAP, I would try different operating systems and/or PCs (and/or physical ports/cables). I understand it's not a valid diagnostic procedure, but people in this forum were sometimes successful, for reasons unknown.
As James said, your problem is probably related to serial over usb. You may want to check whether the board is seen by your os when connected and how the OS sees it (is it missing or just unrecognized?). You may want to post details about your OS, IDE version, whether the Arduino shows up in the serial port list, but don't forget to try a different system if that is possible.

Have you gone back to try and load a known working sketch like blink?

No, I haven't because I cant connect it to program anymore. I'm wondering if it is possible to replace that MEGA8U2 that controls the connection with the PC... As a connection is not possible using the USB. It would probably mean that that MEGA8U2 is damaged, but maybe there are other problems involved.
I've already tried to connect in other PCs and the result was the same.

Well I don't know whether this is really feasible, but since you already know how to use an Arduino as ISP to burn the bootloader from a working Arduino to the problem Arduino, it seems it should be possible to upload your sketch through the "upload using programmer" option using Arduino ISP as the programmer. Since I never did such thing I cannot tell which are the steps to be taken. Also you would still have a nonfunctioning serial connection.