The 7805 gets hot when it has to deliver a big current. The linear voltage regulator works by burning as heat the difference in voltage, so the watts dissipated depend on how much current you draw at 5v. If you draw 1A, it has to dissipate (12v-5v)*1a so 7watts. But the 5v consumption on your board should be very small, so normally that regulator should not get hot. If it gets really hot, that points to a probable short on 5v line, and that short draws big current, which makes the regulator trying to dissipate too much and that process could destroy the regulator.
Perhaps there was a short on that stepper driver. You can measure resistance between 5v and gnd on that pololu driver and compare to the others.
Or perhaps you also have some short on your board. You can measure resistance between 5v and gnd of your board.
Perhaps there was a short on that stepper driver. You can measure resistance between 5v and gnd on that pololu driver and compare to the others.
Or perhaps you also have some short on your board. You can measure resistance between 5v and gnd of your board.
