Last night, I finished assembling a slightly (1mm) thicker version of the case that included 1mm of protective acrylic for the screen. Everything was working great, and power consumption (according to the  MAX17262) was remarkably low. I plugged in the watch and uploaded some new code and... nothing. The CPU went unresponsive. I plugged in my ST-LINK to the SWD ports of the CPU, which only succeeded in frying a voltage regulator. The ensuing debugging marathon lasted until 5am, and involved replacing nearly every component of the watch, including the CPU, PCB, and four voltage regulators (okay, the same voltage regulator four times. It took me a while to figure out that the SWD debugger providing 3.3V on the normally-2.8V VCC line was burning it up). I may have also damaged some of my USB cables or ports, since the watch only enumerates on some of them. I finally got everything reassembled today, and everything works... except the screen. After a long struggle making sure there were no bridged pins anywhere on the connector, I concluded that I must have somehow fried the display at some point. I don't know exactly how; my only theory is that I somehow bridged the 5V power supply to the 3V data lines at some point. Whatever I did, all of the pins on the connector have the expected values when I probe them, which confirms to me that the problem is with the display and not the MCU.

So no big deal, right? A minor setback, but I can just order a replacement (or two, in case I do this again). Well, that's the setback. The display I'm using for this project is apparently only sold through Digikey, who is out of stock until roughly mid-November. I can continue development using one of the other variants, but unless I buy the 01 variant and slice off the frontlight, it's not going to fit in the case. That would have cause other problems, since the PCB is braced against the frontlight assembly. I've emailed FlexLighting and Sharp, both of whom have been helpful in the past, to see if there's anywhere else I can get the display, with or without the light module attached. If I can get it without the light, I can design my own lighting solution (though I'd prefer not to). Otherwise, I might have to wait until November to have a fully-working watch.

Ugh.