I don't know if this has been covered before,
My I pad mini just suddenly died on me, it was fully charged.
I've tried to re boot ..holding home and sleep buttons for 20 secs, also holding home button whilst plugging into computer for 20 secs,
Any other suggestions would be appreciated.

Tried connecting it to your computer? Then trying to start/reboot? Leave it connected for half hour then try. Otherwise take it in to Apple if you can.

Yes I did plug in to computer