MBP 17 2009 not booting on cold boot.

I suspect this MBP 17 2009 has potentally multiple issues.

• For one the dedicated GPU (9600m gt) seems to be broken. I cannot boot without it being disabled (nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00 or with nomodesetfrom a live linux usb stick ). The internal gpu (9400m) works fine then though. I checked the usual suspect c7771 capacitor (https://www.youtube.com/watch?v=pvy-WrDd...) but I measured 1.15V, which seems normal, right? Anyway as I’m fine with only the internal GPU working, this issue wouldn’t be as daunting IF
• the MBP won’t boot from cold. IF it is shut down for longer than 2 hours, it will attempt to boot for a second after pressing the power button, then it dies. The only workaround to solve this is to reset the SMC and NVRAM again. But then I also have to disable the dGPU again, which is rather time consuming (I’m aware that I could remove some .kext so the system won’t try to booth with the dGPU, but I dont know which to remove as the internal GPU is a nvidia one as well). After this I’m able to boot again normally. Once it runs, I can shut down and reboot timely without any issue. It does not seem to matter if I run it on battery only or per magsafe.
• CoconutBattery shows a battery capacity of ~80%. The disk is a fairly new SSD. Already wiped and freshly setup macOS.

Are there any other capacitors that could be faulty and trigger such a behaviour? What else could I try, to get the MBP in a rather stable/reliable state?

Thank you for your help.

EDIT1 SSD is a 1TB Samsung EVO 860. Coconut Battery Screenshot (I would probably not trust it, as I have to reset SMC and NVRAM kinda often):

EDIT2 any ideas?