maybe not dead... WP OS use own partition which cant read on computer....
try use https://www.sdcard.org/downloads/formatter_4/eula_windows/SDFormatterv4.zip (in option select on "format size adjustment")
if card locked, only way to format it and bypass lock password is to use old Nokia symbian phone (check this post)
No chance - tried various card readers and tools SD Card is dead.
It was running with another WP7 Version and Android on it until i flashed that new rom.