Re-attaching Tablet Lithium Ion Battery With DC Power Pigtails
If your goal is to switch the power on and off (if you don't really care about the tablet and absolutely have to hack it) then use a switch. There are surface mount switch that might even be able to fit on the back of the tablet and you might be able to drill a hole in the back to switch it on and off. This is assuming you have any soldering skills at all, and if you don't I wouldn't pick this to be the first project to hone them in. 

A bullet connector might work, (or any other connector) just keep in mind that it will prove difficult to fit the battery and cables back in the tablet. You also have to worry about not shorting out any connector on anything else inside the tablet if its flopping around.

My recommendation: most tablets have a sequence between the power off key or a different key that shuts the tablet down or reset it. If that doesn't work, its always easier to let the battery draw down than open it up.