The SPF-29090 schematics seems to work as follows:
PF3001 SNVS Voltage Is not part of the sequence so its always present when power is applied to the board
Soc PMIC_STBY_REC out its pulled up to SNVS
PF3001 PWRON is Active HIGH
So this seem to work as follows:
When power its applied to the board, the PMIC sequence will start! Its not necessary to press ONOFF because by thefault PMIC ON REQ its PULLED UP TO SNVS
If ONOFF its pressed x seconds, the soc will tie PMIC EN_REQ to GND and pmic will turn off and after pressing again it will de-tie PMIQ ON REC from Ground AND PMIC will Start, the OFF its ok
But the first time power its applied to the board, the ON is wrong because the pmic will start???