8640p 3 screws, 2 under the battery and one 5cm further on the left side (black screw) some force needed to remove the keyboard, i did it with a small flat screwdriver to open and make room for a bigger one and get the clips out at F9 and F12 (2 clips only)

if your battery is not charging on HP laptops, before replacing parts and get your electronic weapons out... try to disconnect all cables, remove battery, press power button for 15-20 seconds, it will flush the "battery memory", plug everything back and power on, ...charging and working :)