Hi,
Firstly the power button sounds fairly normal for this device. It took me a little to get used to.
My best advice is from off - press and hold down for 3 seconds and release. This generally works for me everytime bar the very odd rare occasion that it doesn’t (Perhaps once a fortnight) I use it every day.
The left hand side of the screen shouldn’t be that way. I’ve not personally experienced these half screen issues but there are other threads where members have experienced these issues. I was told that 0.27 bios update had largely resolved them but obviously not if you are also running that?