It seems like you've been unlucky enough to have uncovered an electrical/electronic flaw in at least some of their range finders. I'm Swarovski would like to get to the bottom of it also. Somebody on the production line is getting a bad solder joint or some other such problem that's generating your grief. A couple others have also ID'd the same type problem.
I'd send this thread into Swaro with your bad units and ask for replacements. Once they see their product getting some problematic press via your effort to troubleshoot their LRF units, I'm pretty sure they'd be interested in ensurnig a happy ending to your thread. I do believe they're a class act company - by and large.
Maybe delete this post from your thread. Or if you want, send me a PM and I can delete it so it doesn't look like we've collaborated to damage the Swaro reputation. Hey..., you don't drink while you operate the Swaro LRF units? Just kidding.