I went for a run last week with my Garmin 305 and got caught in 20 min. of light, but steady rain. It was enough so that there was water on the face of the Garmin. I tried to turn it on later in the day and it would not work. So, I let it sit a couple of days and tried again with no luck. I then noticed drops of water under the face of the screen. Anyway, I’ve only had it 3 months so I’ve contacted Garmin about shipping it to a service center; it should still be under warranty. I’ve read the previous threads on immersion and swimming with the 305, which seems to be a bad idea, but has anyone had a problem in the rain? Hopefully they’ll send me a new one, but I may have to carry a ziplock to quickly stuff the 305 into if it starts to rain.
It should be fine in the rain.
Look up the hard reset key sequence and it will probably turn on. Make sure it’s
charged, and then do the hard reset and go from there.
-Jot
I’ve had my Edge 305 for 2.5 years and have ridden the rain dozens of times with no issue. My wife has a forerunner and has never had an issue running in the rain.
Sometimes they just freeze up for no apparent reason and you have to do a hard reset. It’s a good idea to use the web updater and see if there’s any firmware updates after that happens. However, if you have water under the screen, it sounds like maybe you have a bad one…
As others have said, I’ve ran with mine in a hard down poor thunder storm and not had problems.
Mine was fine all day through IMLP last year. If it can handle that it can handle just about anything.
I placed it in the charging dock and turned it on. It did come on, but was behaving strange. It deleted all of my runs last week and some of the buttons wouldn’t work, etc. The moment I take it out of the dock, even after charging overnight, it shuts off. I’ll try the hard reboot, but I suspect it will be in the box on the way back to Garmin soon.
I’ve accidently showered with mine three or four times and it is fine.
The 305 is spec’d for 30 minutes of immersion in one meter of water so your use was well within spec.
Mine was always getting water inside after a run in the heavy rain. It finally died. I contacted Garmin and they replaced it. The new one is fine in the rain.
It should not be OK for swimming but it definitely should be OK for use even in heavy rain.
You can cycle and run under the rain with no problem… But you can’t swim with under the rain 
You just got a lemon, man. They should replace it and I wouldn’t worry about carrying the ziploc when they do. I have been on a 3 hr ride when it was pouring, and a 1.5 hr ride in a steady rain with no problems whatsoever.