I have seen similar issues with my 2 Bolts, and all others I know with an Elemnt or Bolt have had at least one of the issues also. Started happening perhaps 2 months ago, which suggests it is a software rather than a hardware issue. Given the frequency of updates, I surmise it is a problem that is receiving attention, but not yet resolved.
For the power off issue, if you press the power off button and the bottom right button together, and hold down for a few seconds, the device will power off properly. I do this when it hasn't shut down, and the screen is still on, albeit with nothing displayed.
For the crashing, thankfully every time that has happened I have been able to recover the ride, reload the route, and continue the ride without any issues. I rode a 220km yesterday without the crash, so possibly it has been resolved, or I was lucky.
On a 400km ride, both my Bolt and that of a riding partner crashed within a couple of kilometres of each other. Both recovered fine.