Right! Thanks for the suggestions one and all.
Here's what I did - not MY phone by the way, but daughter-in-law to be.

On one piece of advice, I put it in the freezer of my refrigerator for a few hours.   No good.

Took it out and there was condensation all over it.

Wiped it off, and as per Gnu's suggestion, put it in the microwave on high for 3 minutes.
When it started arcing and burning (the smoke really stinks) and the plastic bits melting after THREE SECONDS. I took it out. It was hot.

Now it won't even turn on. Oh well....

Thanks.

Seamus