Samsung SCH-A970

anyone else having this problem? My phone just shuts off, like the battery is dead, but it fully charged.. leave in in the charger all night, and anywhere from 5 minutes to 2hrs later, take a look, its shut off.. turn it on, and once again, shuts off in a little while.. ? checked battery connections, all good.. can't push a button with the lid closed and shut it off, took it out of the carrier, lay it on the table, still shuts off?