Computer not turning on after battery replacement

I recently replaced the battery in this MacBook. It turned on right after before turning right off again and now it does not turn on at all. I've attempted power cycling, SMC reset and even switching the Magsafe board with one from a known working computer. The charging indicator light goes from green to orange as if it is charging the battery and the computer appears to respond to keyboard inputs like SMC reset (light flickers when I do it). But I still get no signs of life, no display, no chime, no fanspin.

I also tried powering it on without a battery and with the old battery but it still does not turn on.

I'm completely stumped, unsure if my board is dead, help would be appreciated.