hi, bro copernicus.

answering your question:
1&2. yes, i have opened my web browser and go to settings and tick "Enable Rotation", but still cannot go to portrait mode

3. when opening the keyboard while holding my phone vertically -> display still lock at landscape.

but, i noticed one thing. when typing or when i opened my keyboard while my phone is still locked. the LED on keyboard didn't lit. it only lit when turning on my phone. could this be my keyboard slide sensor problem?