describes some previous problems with ground connections on Convoy’s lights, and shows a ground wire as one workaround.
Looks like they’re still wrestling with the problem, and not doing well.
Here’s my recommendation, as I posted in that earlier thread at Help - advice for Convoy red S2+ driver ground - #7 by hank
(a link there points to more discussion of this elsewhere, too)
Since it appears Convoy applied those solder blobs, well, I’d complain if I got them like that.
It’s a known problem — the usual retaining ring won’t fit down over extra 7315 chips on the spring side of the board.
Convoy needs to find someone with a laser cutter or a good file, and notch those retaining rings so they fit around the chips.
That gives an excellent, reliable ground.