Superpad 7 (10.2") Replacement Battery?

Hi all,

My daughter's Superpad 7 stopped powering-up fairly soon after she got it. (I believe it's a Superpad 7 Allwinner A10.)

Anyway, I've finally got round to looking at fixing it but it was bought a while ago & I can't remember the exact specs. I've been looking for replacement batteries online but am not sure which one to buy; the one inside has no markings whatsoever. eBay is full of batteries: 3.7v 4000mAh, 7000mAh, 8000mAh. Some for Allwinner 10, A13, A20, A23 - you get the picture.

I would be most grateful if anyone here can enlighten me as to which of these (if any) I should buy. I'm 'fairly' decent with a soldering iron so that shouldn't pose a problem.

Many thanks for your time.

zarathustra =]