I don't think I did it in the end, Dave but I did wonder about the battery on what had been my Nexus 2012 tablet and is now something mum (mostly) plays a few patience card game on before bed... As I think we might have been through with fitting a sdd in my Asus laptop, youtube can hold an answer to at least some of these problems/tasks. I did find one on opening that particular tablet.

I've not looked up my current Wiley Fox phone.