Well, my buttons finally fell inside the housing, and 3FVape has arranged for a free replacement (after sending video proof). Can't fault their service at all, other than it took a full week to resolve (mostly waiting on "the manufacturer" to respond, and my mistake for making the videos private which added a couple days)
I asked if they could "upgrade" me to one of the Sunlay models with me paying the slight price difference, no response yet. After watching that video tpat posted earlier, I'm convinced it's a Kangxin board inside, and I think I can live with the fixed 510.
Alas, my attempt to re-glue the buttons back in my current one ended in disaster. The hot glue part went well, and I braced the back of the buttons in place with a couple of trimmed wooden toothpicks inserted between the soldered leads before applying the glue, and the buttons became super solid with almost no chance to come back out like before. Was pretty happy with that result.
But, I got a bit too enthusiastic with the amount of glue I used, and didn't notice that I had glued up a fair amount of slack in the display ribbon cable, so when I went to reassemble and lay the display into its cutout in the top housing, the ribbon cable snapped in the middle.
Since the darn thing was shot at this point, I went ahead and tried to remove the 510 connector. No joy, the solder they used on the negative lead is preventing it from coming out, and the stuff is more like a weld, I've tried a hot soldering iron, a butane torch, and a file, and just couldn't remove enough of it to allow the connector to come out from the top before I decided to give up. I may get motivated again if I come across a replacement board for the housing.
EDIT: As a side note, the USB board is a balanced dual battery type, they did wrap both boards in non-conductive clear tape to prevent shorts, and reinforced all the solder joints with hot glue, and the main board assembly is resting on a rectangle of foam rubber. So while it's messy, it's mostly secure in there.
