I powered on board 3/4 and the processor died instantly, I couldn't understand anything. (Status LED won't turn on as well). The first thing that'd overheat before each board's death would be the 3.3V voltage regulator.
So I took out board 4/4 and along with soldering headers, I removed removed the 3.3V regulator and soldered a new one which I bought locally(Both had 1A rating).
Now this board worked fine, I had my finger on the processor all the time. I connected stepper driver one and it was good. As soon as I connected the second driver, it started to overheat rapidly. I mean very rapidly!
So I pulled that driver out and it was back to normal temp. I tried to limit the current by reducing Vref on driver and connected it again, it overheated! I pulled the driver out maybe a second late but before I could do that board was damaged.
Damaged in a way that it works fine, only the processor maintains high temperature of 80-90 degrees.
IRUN Current = 600
TMC2130 Vref = 1.15
Also when the processor was fine, onstep app would not allow alignment, it'd say "Hardware Fault." And the status tab would show "Motor/Driver" fault.