Remove the battery again also disconnect the power adaptor so there is no power to the machine . hold down the power button for 60 seconds then reinstall the battery and reboot with power cord installed . If this gives you no joy it may be a bad stick of memory . If there is two sticks of memory in the machine remove one and try to boot then try the other . try each stick in each dimm slot as it could also be a bad dim slot. If the computer boots with one stick alone try the other stick alone in the same slot to see if that stick is bad if you need to replace memory remember to use the same type speed and frequency and latency. If this gives no joy then connect to an external monitor through the hdmi or vga connector on the laptop. If this doesnt work then you may be looking at a bad APU which is a major fix . Hope this helps
Teardown video to help
https://www.youtube.com/watch?v=PjCtMtTdB7Q