I fixed my bricked arduboy that had a broken reset button by opening it up to realize that the battery was disconnected from the solder points. So i soldered it back and it works just fine.
Was it bricked or dead before you opened it up? You may have broken the battery tabs when you opened it up. BTW soldering to those tabs and the Li-Ion batteries can potentially be explosive.
it was dead, turning the switch on even with power didn’t work
so i opened it up and found that the battery tabs were disconnected and the battery was sliding around
so i soldered it back and it’s fine although i have to open it up to press the reset button
it was also bricked and i had to use some wire to act as the reset button