Flash devices are made of printed circuit board and NAND flash memory chip. Here the NAND chip stores the data. Once short circuited like the case above, the whole NAND chip is destroyed/burnt out. Hence recovery of data can't be imagined. In case of HDD, the data is written on the disk platter, making recovery possible when if the circuitry leading to the writing head gets damaged. Data is still intact in the platter. Hence of retrieving the data is still a possibility. Hope it's clear now.