@impro use something like this guide to at least get to it [guide|127053] . Yes the battery is adhered to it but can be replaced by gently using a non-metallic spatula etc. to jimmy it loose. Stick with a battery to is made for your device and there are no large capacity batteries for it. As for the heat gun, it is only to be used to heat and soften the glue. Do not blast the heat straight onto your LCD and keep the heat gun moving along the edge. To much heat will burn your LCD screen. There is no exact science for that heat gun but usual temperatures for this type of job is between 80 and 100 degrees Celsius with 80 degree Celsius being standard. To hot and your LCD will get damaged.