Original battery was about the same in size and capacity as a BL-C4(nokia 6310 battery).
Now it has a HTC One X (3.7VDC 1800mAh 6.66Whr) battery in it.
Here is it:
Lets dent it a bit so it fits (carefully of course)
Works perfectly fits like if its the oem battery
HOWEVER, i do not recommend you to do the same. As its not so good for a lipo battery to be dent as much as i did, and im not sure if this will be safe. So keep in mind if you do the same, its your own responsibility.