OK, I'll risk a Pestogram.......
On the original logic boards (RAMPS V1.4) the step sticks are at some risk if you leave the USB cable and computer source plugged in and shut down the PSU to the printer.
The problem is most prevalent when using TMC2100 step sticks.
What happens is that the board power goes down, taking the +5 and motor supplies with it.
However +5 is still coming into the board through the USB cable.
This then attempts to feed the the logic chips through one path or another.
For TMC2100 drivers in particular (but even for A4988's), this is a major no-no.
Their data sheets have very specific warnings about back biasing the output logic more than one diode drop's worth (about -0.7 volt).
So the internal circuitry back-biases, overloads, and then the magic smoke escapes the packages and they become very tiny paperweights.
The solution is quite simple and cheap to do.
Add a 1 ampere rectifier (preferably a Shottky type) between the +5 and +V (12 or 24 as the case may be) rails so that +V cannot ever be more than that rectifier's forward drop below the +5 rail.
Cathode to the motor voltage rail of course so it doesn't feed motor voltage onto the +5 rail.
I added a 1N4002 on the unused second extruder motor socket.
Some will claim this is a myth.
But it happened to my printer, so trust me it is no myth.
Snapping noise, the stink of burned plastic, and a step stick down the drain.
But if you are not using the RAMPS board and Pololu-style step sticks, it shouldn't be a concern for you.
Some people have resorted to cutting the +5 wire in the USB jumper cable, but I prefer not to modify tiny wires in molded cables.
The rectifier works perfectly.