Here's something you can try with the battery. It works on my v710, and a lot of the OS is the same on the two.
After you plug it in, force the ring style to "Vibrate" or "Vibe and ring". That should shut off the charger.
Normally, if you have your phone set to Vibrate and plug it in, the phone will automatically change it to "Loud" or some other non-vibe setting (since it doesn't want to vibrate the phone while it's connected to a cable). For me, forcing it to "Vibe and Ring" after I plug it in cuts off the charge circuit until I unplug and replug in the phone.
Hope it works for you.
Can't help on the modem part, though