Sometimes trying DOES hurt , so use this trick only when you have decent knowledge of battery acids , exploding things and 220 volts...
Sometimes batteries can be "kick started" by putting an extremely high current through it for a very short period of time. On the other hand.. they might explode.
Safer trick (but still dangerous) is to heat up the battery pack a little , sometimes it gives some current after that.
3rd and last attempt : disassemble a complete battery pack carefully , examine the cells seperately and try if you can find those.
Again .. if you set your house on fire , kill your grandma or pour battery acid on the cat.. you have been warned so don't sue me.