Bought a tinyduino main board from a local retailer - it was the starter kit that comes with the board, USB and proto board, so it had the bracket on the back to hold batteries. Using this format because of size (making a cat toy) I desoldered the bracket.

Soldered wires to the board at the locations marked here:



While soldering, I slipped and accidentally bridged the + to the SMD component to the left of it in the picture above. I desoldered the bridge and ensured there was no connection. I mention this in case heat damage, or a possible disconnect of the SMD is causing my problem.

The board will not run under the power of 2 LR44's or even 2 AA batteries. Even tried 3 AA's in case 3.1v wasnt enough.

But it runs when plugged into my PC via USB.

Did something break when I messed up the solder (if it did I'd imagine it would NOT run under USB, but it does), or am I doing something wrong? I'm at a total loss here.

The component is just a 10uF capacitor with ground on the top and VCC on the bottom. If '+'(VBAT) was shorted to VCC, it would just turn on with battery power, if VBAT was shorted to ground, you'd probably notice- However USB power should still work, because it's on the other side of a p-channel mosfet.

You could try shorting the + to the lower side of the capacitor(VCC) and see if it powers up- this might be a useful temporary solution if the power switching circuit was damaged, but don't plug the USB cable in at the same time as the battery.