Mine was exactly the same this morning. I've had mine 3 weeks, double checked it was waterproof as it was a present from my wife and seconds into the pool it went blank, I took it off right away and now the screen is damaged and not connecting to my phone. Poor!
Same here.... FR735XT Got blank after a swim. Unfortunately out of warranty period. Will anyway contact Garmin for their take on such issue.
That's too bad. That is not how they should be. I bought a 735xt four years ago, and it just died due to water damage. But I swam 2-3 times a week in a pool and then probably 30-40 times in the ocean over those four years either with triathlons or surfing. After a swim last week, I noticed what looked like water around the edges of the screen. I thought it might just be condensation although it was odd that it had not happened before. Sure enough, after my next swim the watch died. I noticed more moisture out of the pool and a couple of hours later it was blank. So I guess some of these do work as intended, at least for four years in my case. I was thinking to get another one but after reading these stories maybe I'll go with something else.