hi, i think that it is a battery problem, i know first hand because my ipod touch died but all it needed was a new battery, you should get yours changed, as for the accessory not supported, im not really sure (sorry) try reseting it again!
try connecting the sd card by itself and install a program called easeus partition manager home edition http:// then open the program and look for the card. then rightclick on you card, then click on format partition