How to recover Arduino Nano from death

Hi, I am using an an arduino board V3 in a system and I killed some of them .

-One was because one wire connected to 5V touched GND or some other, while arduino was connected to USB.
-Another was testing a board that had an shortcut from 5V to GND, and also was supplying 6V to some analog inputs.

Both arduinos doesnt respond anymore, either external supply neither USB supply. I think this arduino board have protections and so, and seem difficult to me to kill so easily an arduino, just with 5V supply. So, there is some recovery that I could try to recover them? Or some part of the board I should check/repair)

Thanks in advance

I am afraid not. The arduino does have a voltage protector but it is only wired up to the wall power connector and the AREF pin. grounding the 5v pin is one sure fire way to kill your boards

OK. Thank you very much for answering so soon

A 5V to gnd short on the Nano often fries a Schottkey diode (I think that it's D1) that connects +5V and Vusb. If that's all that's failed, you can replace that SMD diode with another one or with a carefully connected thru-hole diode.
Ciao,
Lenny