Why does my Q10 screen go black/disabled randomly whilst in operation?

Hi Gang. Hoping someone can help... I've got a Q10 (only accessory is a screen scratch film) and recently the problem with the screen randomly going black has untenably increased after updating to the new OS.

Key facts: The ONLY two ways the screen will come back is:
A: I restart by either removing the battery or pressing the power&mute button for 8 secs (and currently its now going black as soon as the hub initialises) OR
B: It <always> comes back when I plug in the USB cable connected to either power or pc and this seems to job it back to normality for a hour or so.

The phone is still operating when this may happen: for one example in the middle of a phone call (usually when i activate speaker phone) the screen will go black whilst still talking fine� but if i try and end the call/deactivate the speaker phone/do anything I hear the error beeps when i inevitably start mashing the whole keypad - but the screen will not reappear or read <any> finger gestures or singular power button pressing.

Btw. The phone passed all tests on the BBVirtualExpert App.
I have just installed the new OS 10.3.1.1779 (but it was happening before)

I bloody love this little phone but this is seriously a fatal issue. Anyone have any ideas? Anything to try or should I repair or get a new one. Thanks in Advance.
Ewan

Have you contacted BB about a replacement? Since it seems a different OS doesn't seem to help? Maybe this is a hardware issue or an internal cable connector issue?

Hi - Thanks for replying :)
Well, I bought it off ebay - new in the box/unlocked, so no recourse i guess?... Is there some kind of official Black Berry Australia phone number or email? - for the life of me i can t find any way to contact BB at all. Perhaps I should take it to a phone repair place but I got a feeling thats going to be a waste of time/$ if its not a common problem. any further hints?
Thanks!