Just for the record: replacing the internal card with 64GB micro SD (SanDisk Ultra) works fine in Kobo Aura HD, but now my Kobo Aura HD has no touch-screen function at all --- i.e. on replacing the top "bezel" thing I got into the same problem as a year ago (when I successfully upgraded to 32GB), but now it seems the chances of making it work are even narrower --- a year ago I lost just a bit of the screen and by persistently removing and re-attaching the top cover (for about 5-6 hours) I managed to make it work. Now the whole screen is unresponsive (except when I press some part of the perimeter, then some parts of the screen are responsive).
Any ideas? Tomorrow I am going to buy another Aura HD --- the question on my mind is whether I should do the same to it as well (and lose another 130 GBP) or should I just stick with 4GB + 32GB external configuration... I'll sleep on it