Apologies for my attitude last night, one thing after another yesterday.
On my model.. A21s it's IS volume down + power, every other model is volume up+power. The reason I know that is, because when I first needed to do thia, volume up + power didn't work, all that does is just is just restart the phone. It was only after trawling the internet for ages, I found out it was actually volume down for this model phone, and as soon as I did that, it worked immediately, and did do every single time after that until now.
I did a factory reset this morning in the hope that would fix whatever's wrong, but it hasn't, it still just goes back to the battery percentage dial.
Yes it's connected to my laptop.
Have tried 3 different cable's.
3 USB ports.
Same result every time.