MightyHat - Unable to Upload Sketches - SOLVED

[Jason]

Problem Description:
Using FTDI programmer, unable to upload sketches to MightyHat.

Investigation:
- Raspberry Pi wasn't receiving any data from a test mote which was receiving acknowledgments [ACKS] from the MightyHat. Didn't notice this as a clue at the time.
- Decided to check continuity and found that there wasn't continuity from the FTDI header to the ATMEGA chip. Found there was no continuity through a via that was under one of the buttons.
- After removing the button found corrosion.
- This was likely due to the water I was using to clean off the flux from soldering. It was De-Ionized water but I obviously didn't do a good job of removing all of the water.
- Probably would have been good to blow out under the buttons after cleaning off the flux residue.
- See attached picture.

Root Cause:
Corrosion due to water stuck under button after cleaning flux from soldering. This was my mistake from when I soldered the kit together, it was not received this way.

Solution:
Using a single strand from a ~20AWG wire, clean out the via. Then solder a single strand of wire in the via. Check for continuity and its back up and working.

Notes:
- Flux residue in picture is likely from the flux core solder I used to help desolder the button.
- Red herring: I just attached a Nokia Screen to the MightyHat, first backwards and then correctly.
How do you attach a Nokia Screen Backwards? - Sourcing screens from AliExpress, not all come in the same orientation or footprint as the ones that used to be stocked in the LowPowerLab store.
- Lesson learned for me, when designing PCB's it seems to be a good idea to avoid placing vias underneath components if possible to avoid water and flux from getting stuck in the vias.

[Felix]

Great debugging and resolution, thanks for documenting this!