Hi, I know this was ages ago, but did you wait for your watch to die and then charge it or did you just start charging it again? I'm having the exact same problem of not being able to start an activity or turn off my Forerunner 235. Thanks!
I'm having this problem today, did you find an actual fix?
I've been having the same problem with my 235 for the last couple of months. Each time, I have to reset the watch by holding in the three single buttons (not the up-down buttons) for a few seconds until the watch shuts down. After a little while, a dab on the start and it starts up and behaves normally - until the next time. I'll try always charging via the Garmin app on my PC but I'm not holding my breath. I've had the watch for a few years and this is a new issue.
Since writing the above, I've googled for resetting the watch and the above remarks need amending. They work but this link is a clearer explanation. www.youtube.com/watch