Hey folks,

today I installed a new flight controller, checked everything for continuity, plugged in the lipo with a smokestopper in between and was satisfied with myself not to have produced a short circuit. Then I wanted to configure the FC in betaflight, plugged in the USB, got a few blinking LEDs, but before betaflight connected, there was some weird smell and the LEDs went out. I then unplugged the FC and found continuity between ground, 4.5V and 3.3V. The RX that was connected to this port is fine, or at least has no continuity. There also is no continuity between 5V and ground on the FC, so I suspect some voltage regulator that is driven by USB only is burned through. Is it possible that I missed something in my procedure and destroyed the FC by faulty installation or can I expect to have gotten a faulty unit? I hope I can return it, not sure because I obviously soldered to it already, if I can not return it, is it possible to replace the faulty voltage regulator?

The FC could well have been faulty from the factory but it's difficult to know. It's also possible that a stray minuscule solder ball or stray whisker of wire moved after you did the initial continuity checks thus causing a subsequent short circuit. You might never know.

Whether the vendor will offer you a free replacement is going to be down to the vendor. Some are sympathetic while others are not. Usually it is the vendor who ends up taking the hit in such cases and not the manufacturer because often it is just too much hassle for the vendor to try and argue for a replacement from the manufacturer unless it can be proven that there is a bad batch of more than one with the same issue.

If you can locate and identify any fried voltage regulators on the board then yes it is possible to replace them if you can source replacements and have the required soldering skills to do so.

Thanks for your solid answer. I am fairly confident, that no whiskers or solder balls where around, since I brushed down the whole board with a toothbrush and isopropanol. I will call the vendor on monday and hope I get a positive response. If not, I will have an opportunity to sharpen my soldering skills, the previous FC is waiting for a new MCU anyways...