In the last couple of months I've bricked three Nanos. Plus a Leonardo. Just happens out of the blue for no obvious reason. No com port showing on some, hanging on Uploading on others. I suspect my laptop and intend putting some protection between it and the nano. First thoughts are to drop the voltage (a bit high at 5.1v but within spec) with a diode and insert resistors in the two data lines to reduce any power surges. I was going to find how high I can go with the resistance value before the USB stops working then lower it 10% or so. To this end I Just ordered some USB breakout boards. I was wondering if this is a route others have trodden and if so what advice could be offered.
btw I've tried using a UNO as a programmer to re-install the bootloader and can't get it to work - complains about wrong board codes. Anyway even if I reinstalled the bootloader, if indeed that is the problem, that won't stop me bricking them again so I'm trying to get to the source of the problem.