Will not power on with power button. Only when attaching AC adapter

Macbook was brought to me because it was not powering on. I opened it up, pulled the battery, reattached and plugged in the power adapter. BOOM. Powered on, logs in everything working as it should. Power down the device to see if it works as normal... Nothing. So I do it all again. Same result. Powers up after battery pull then nothing after shutting it down.

I run diags on it and they come back with SMC error, Power Management error, and Battery error. Attempt to reset SMC and the light indicator on the magsafe seems to be telling me that it worked but it still does nothing when I try to power it on with power button.

I replace the logic board and I don't have to pull the battery every time to get it to start but it still does not fix the problem. Power button still provides me with nothing I have to attach the Magsafe adapter for it to turn on.

After it's on and I press the power button to shut it down at login it shuts off immediately and turns itself back on again. If click the shutdown button on the login screen then it powers down as it should and stays off.

I ran the diag once more and the logic board replacement got rid of the SMC and Power Management errors but the battery error still remains.

I replaced the battery and nothing has changed.

TLDR:

• Macbook only powered on with battery pull and only after ac adapter attached. Once on it stayed on with or without the magsafe attached.
• Replaced logic board and battery.
• Still have to attach magsafe adapter to get it to turn on. No longer have to pull battery but power button remains useless unless the device is already on.
• SMC and PRM reset seem to do nothing.

Any help would be much appreciated! Thanks in advance.