Originally Posted by
Rickmaersk Phone was updated to android 10 ... Recently I ran out of battery power
That's a good way to pay for a replacement battery. Recharge at 45%-50%. If it gets down to 40% and you can't charge it,
turn the phone off!
Eventually I tried a factory reset (Android8)
No, a factory reset just deletes anything you've done (apps and data), it doesn't change the OS.
When it boots up it take about 30 seconds to draw an android logo that should take about 2 seconds. You can see each frame. I'm assuming it might be a display specific issue because if you actually had the patience you could get it to (for example) play music and it was smooth not glitchy.
It's most likely some app you have running at startup that's consuming almost all resources. Start in
safe mode - if that fixes it, it's an app.
Can anyone suggest a way of diagnosing if the screen itself is faulty of if it's another hardware issue.
Not without replacing the screen or connecting the screen to a different phone.
