Hi tridge,
Looks like that did the trick! WiFi is working again. It was indeed the lower pad (TP4). It had a weak pull-up on it, so I pulled it down with a jumper. The upper one (TP5) was already at 0V.
I might have left the jumper on for too long though. It seemed to reboot a whole bunch of times after flashing. Unfortunately, I didn’t keep a log of those printouts and my memory is quite volatile.
The firmware upgrade web page showed that the ArduPilot version was 2017-07-29 (3.6.0-dev 6fc59437) and the transmitter at 2017-07-24. I didn’t record the version of the Sonix board firmware before I bricked it, but presumably it had a similar version as well? Is this an expected firmware version?
I updated to the current latest (and also stable?) of 2017-10-14 dfd2d838 on the Sonix, 2017-10-14 (3.6.0-dev d84c8a4f of ArduPilot, and 2017-10-14 of transmitter.
I’ll see if I can reliably break it again in the next few days with the latest firmware and maybe with the other version. Thanks for the very prompt response.
These are the pins that I’ve poked so far:
I was planning on taking pictures of all the boards (with better lighting than my one above) and eventually annotating all the pins and submitting a PR to put them on the SkyViper doc page or similar.