|Haven't heard from my chum at Apple yet… But did drop into my local Apple store and had a word with one their techies…|
He suggests you try a PRAM reset which done as in this link…
You "will": need an external/plug-in keyboard (usb obviously).
Ensure system is powered down fully; plug in the keyboard and then follow the instructions as above.
You may need to do the reset 3-4 times overall, rather than just once...
He also does suggest you drop into an Apple store too; as an ad-hoc (wait as in a doctor's surgery etc - with no appointment) visit may suffice to help resolve it all… Otherwise book an appointment with Apple as that may allow a little more time/input.
Also if you search via google using the words/string:
macbook reset pram
you will find a lot more information about this routine.
And if you use the words:
keyboard mouse frozen macbook reset PRAM
you will very likely get the above link - and others that discuss your situation variously - e.g.
Suggest you have a read and try the PRAM routine?
Once you press the power on button you have to get the PRAM command entered - before the grey screen arrives…
If things don't resolve… then definitely go talk to Apple and take the laptop with you of course.