Dell 7577 disable dGPU

Could someone please help me disable dGPU? Battery life is terrible (2hrs compared to 6 on Windows). I tried following RehabMan's guide but so far no luck.

All my files are located here: https://github.com/wadimw/dell-7577-hackintosh

I tried

• adding Method (_INI) { _OFF() } to SSDT-12 in Scope (_SB.PCI0.PEG0.PEGP)
• inserting calls to _PS3 into _PS0 and _PS1 in SSDT-12 in Scope (_SB.PCI0.PEG0.PEGP)
• inserting call to _OFF into _ON in SSDT-12 in Scope (_SB.PCI0.PEG0.PEGP)
• inserting call to _OFF into _ON in SSDT-2 in Scope (_SB.PCI0.PEG0)

either these don't work or I'm doing something wrong. I'd be grateful if you could look into my files and help me with post-install config.