i'm facing a similar problem, but playing a bit with the on/off button i'm able to switch on the device.
If you fill a bug for this, post the link here, so i can leave a comment.
I was connected to a laptop via usb and didn't see any issues. How are you trying to switch it on? Press and Hold the power button. If the device is mounted, it will take a few seconds before booting up.
I too have seen that connected to my computer it sometimes refused to turn on. But since this behaviour was erratic and non-reproducable, I did not think of it again.
Removing the USB cable was enough for me.
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I do have another problem, or problem, oddity. When I connect the usb cable to the phone, sometimes, nothing happens. I disconnect the cable, either on the laptop side or the phone side, and wait a bit and then reconnect it and suddenly the device knows it can charge and starts doing this and asks me in which mode I want to connect.