It has a second chip (AXP202) that is responsible for battery /power and has the button directly wired to it. That's why I believe deep sleep should be possibl

It has a second chip (AXP202) that is responsible for battery /power and has the button directly wired to it. That's why I believe deep sleep should be possible. If it needs to reboot instead, fine I can accept a ~second delay. But again, the supplied firmware boots 5 seconds and I've no idea why and how to rectify it.