I got a Particle Argon recently and was using it for a school project. Everything was working great and I was powering it off a small LiPo and USB depending on what was most convenient. I had to use two digital pins to connect to my device and soldered them on to I/O pins directly because everything had to fit into a small form factor.
I wanted to reuse the device, so I desoldered the previously connected pins. Since then, I could not power the Argon using either a LiPo or the USB connection. It downright fails to start. However, when I connect the output of a LiPo directly to the 3.3V pin and ground, it switches on the device and as far as I can tell, everything is working properly (connects to wifi, blinks led, etc).
When desoldering, I made sure not to apply the heat for too long for fear of frying anything. But that is the only explanation that I can think of for why the USB and LiPo power sources are not working. Do you also think this is the reason and is there any way I can fix my device?
EDIT: I used a multimeter to check the potential of the VUSB pin and Li+ vs ground when connecte via USB and LiPo respectively, and they read the potentials that they should (~ 4 V and 5.2 V). I am not sure if this information is of any use, but hopefully, it will help with troubleshooting.