I've only really had one tama die on me - it was my V1 - 21G - i just forgot about it one day, it was my mum's birthday and heaps of things were happening??? It died and i never played with it again - the buttons had started not to work properly anyway.
My latest V2 tamas are 23G (2 of them) and 10G (the newer one) . None have died yet.....
Mine died from eating too many pickles. And drinking too much off branded kool-aid. Poor thing. I warned it but does it listen? Nooooooo it never did. Actually mine just died because it was sick and i fell asleep while it was still awake and when i woke up it went bye bye a go go.