Arduino Mega 2560 and Ramps 1.4 power overload

Evening all,

My apologies if this has been asked before, I did search through the forums but didn't find anything quite like my issue, so I'm hoping a more learned mind may be able to help point me in the right, or a better, direction.

The other day I was configuring my anet a8 printer with a new ramps 1.4 and mega 2560 controller, and didn't realize that I had, I believe, 3 power sources into the arduino. I know my mistake here was not having removed the d1 diode on the ramps shield, and so it didnt even cross my mind when power was coming in via the ramps shield, the usb connection, and the ps-on/5v/vcc jumper was bridging the ps-on/5v pins.

Shortly after, I lost power and usb communications with the mega. I promptly removed the ramps shield and found a blown voltage regulator on the mega. Having replaced that, I still sm unable to restore communication with the mega via usb, however the ramps shield still powers properly, and I can still run my 3d printer from the program currently on the mega, so the main micro seems to be functional.

I am at a loss as to how to proceed with determining if the 16u2 is blown, or if there may be another component that needs to be replaced as well. I have attempted to place the board into dfu mode to no avail, however the board doesnt quite match up with others I have seen. It is a mega 2560 r3 for sure, but a osoyoo knockoff. Is there an alternative way to enter dfu mode? And might there be any other components that may have fried without me realizing? There was no magic smoke or burning, just a light pop as a piece flew off the regulator.

I realized need to add the following: I can see the mega when its connected via usb, on any device, be it laptop, tablet, or phone, but it doesnt respond to communication. All power seems stable across the board, 5v and 3v3, whether it be from usb or from the barrel, tested up to 12v in on the barrel.

Again my apologies if this has been covered before, if it has, I'd be more than happy to scour over any threads that may be related.

Thanks in advance :)

Regulator blown?! Those things are normally pretty robust with built-in protection against overcurrent and overheating.

That you can see the Mega means the USB/TTL chip is working, but that's all you can tell from that part.

Blown regulator implies you did a bit more wrong than just overpowering it. Could be a polarity reversal, that'll blow such a component. Very likely the controller is blown as well in that case.

Just get a new one. And a few spares, when you're at it. They're cheap, not worth too much time trying to fix.