MacBook will only power on if the battery is unplugged

Hi so I have a problem. I found my old Macbook Pro 15 in non-unibody from 2008 I believe. I am really inclined to get it to turn on. So far the only method that has worked to get it to turn on is if I remove the battery, hold down power button for 10 seconds, plug the charger back in and continue to hold power button for 10 more seconds then release it. Only then, do i hear it turn on and the fans spinning. However, I get no display on the screen whatsoever. I don't know what to do any advice will be helpful. I want to open it up and maybe check the display cable but I don't know if that will help.

Also,

my battery isn't in the best condition, it looks like it is peeling apart or something. I was thinking maybe I can just tape it up but I don't know. any help/advice will be appreciated