Hello, my Nano (clone) and Leonardo (official) died after presumably the passive USB hub's voltage rose above 5v (passive hub).
Both devices died at different times on the same hub after an unrelated device made by me was plugged into the hub which is known to require USB power isolator that I didn't use. Any other device plugged in still functions normally.
IDE doesn't recognize the devices and Windows recognizes them as "Unknown USB Device (Device Descriptor Request Failed)" they were both flashed using Simhub's Arduino Flashing tool, both worked fine until this issue.
Devices still have appropriate 5v and 3v on the rails, their LEDs function correctly.
The Nano's LED lights up whenever a button/encoder is used meaning the sketch is still functioning. I don't have a way of confirming the Leonardo's sketch is functioning.
Both devices simply had buttons on them and the nano a standard encoder, no external power was supplied. Leonardo came back to life for about a second after restarting it once but I've been unable to replicate this a second time.
I am a newbie at the subject, I'd really appreciate any input, thanks a lot for anyone's time.
I tried the reset buttons in all their capacity, shorting the voltage regulator and checking if the diodes and voltage rails are healthy, all of them work including the sketch on the nano, the only problem about both boards seem to be the fact they cannot communicate with the computer, not with IDE, not with windows aside from being unknown devices with descriptor requests failed.
If anyone has any idea to salvage these devices I'd be happy to hear it.
For the Nano you can remove the serial-to-usb converter (at the bottom of the board) and use an external one or a so-called FTDI cable.
If that works you can consider to replace the chip that you removed.
For the Leonardo you'll have to replace the 34U4 microcontroller and burn the bootloader.
Basically, I was just making a buttonplate for sim racing using a program called simhub which has a tool for flashing arduinos using the assistance of a GUI for simple features like LEDs, button matrixes, encoders etc while handling telemetry with videogames, nothing crazy, just very simple code made convenient to flash.
Leonardo had about 8 buttons wired to digital inputs and the GND, worked as expected.
Nano had a matrix with about 16 buttons attached and 2 encoders, worked as expected.
I lost the Leonardo and Nano after plugging it into the same passive USB hub as another project of mine. The other project (completely unrelated) is a simracing wheelbase; it has a motor with a 24v 20a PSU and requires a USB power isolator which I had not used.
Both Leonardo and Nano functioned for about I believe 10-30 minutes on the hub (died at different days) while I was playing around with my setup, the Leonardo functioned normally for about a day plugged in and died around the time I plugged in the wheelbase to the hub.
Same hub took the Nano out a day later, connecting the dots I believe there is a ground loop/issue with the wheelbase (3rd unrelated item connected) that overloads the USB hub and likely fried some part of the Arduinos.
OK. Thanks. I now see that SIM in this context is a sort of auto racing simulator/gaming (eco)system and you are using Arduino with special firmware to integrate controls into this system.
From my quick reading of Sim Hub documentation it looks like it is compatible with only atmega32u4 based arduino devices (Leonardo and Pro Micro) because of the need to alter the usb vid/pid codes and this would seem to preclude a Nano.
If up to 24 volts has leaked onto your USB bus then you are fortunate that the damage was quite limited.
Simhub sees the nano and runs a computer side keyboard emulation to make use of it, nothing extraordinary should have been done to the Nano as it wasn't an input device by itself. As for the 24v, only a small amount of it should bleed to the USB but it seems that is sufficient to kill the Arduinos, but the Logitech Extreme 3D Pro connected to the same hub survived both instances.
Unfortunately this is probably a correct assessment. It is laudable that you want to repair the board and get more use out of it instead of turning it into e-waste, but the fact is that it likely doesn't make sense to do so from an economic perspective.
The cost of a replacement ATmega32U4 microcontroller is a significant portion of the cost of a replacement board. It will require precision soldering work to desolder the bad SMD chip and replace it with a new one. Then you are faced with the task of burning the bootloader on the new chip (a fairly straightforward procedure, but still can end up being time consuming if you have never done it before). And there is still the possibility that other components on the board were damaged (though the ATmega32U4 is certainly the most prone to damage). Perhaps you will never have confidence in this board even if it does appear to have been successfully repaired.
From an economic perspective, it really comes down to how much you value your time. However, if you have the appropriate equipment for working with SMD components and feel the endeavor is something you would find educational or enjoyable, then it could be worth doing even if it doesn't make sense from a purely economic perspective.
Thanks to everyone for their responses, since I am new to the subject I didn't know the scope of the damage and the Leonardo micro-controller needing a replacement is a reason enough to turn it into e-waste, as for the Nano I may try to use an FTDI cable or replace the USB to serial converter.
This has been incredibly informative, thank you for your time.