Hello everyone,
I have an Acer ES1-533-C39G and I want to install Windows 7 but there is no way to change it from UEFI to legacy mode because the option is grayed in the bios. I made a usb stick using rufus with gpt partition scheme for uefi (non cms) system but every time I get "no bootable disk" message.
So, I need help to get an unlocked bios for this model.

Thank you.

P.S: I attach screenshots for the configuration I tried in the bios tabs and a screenshot of the configuration of rufus using the lateset image of W7 by teamos.

You need to first enable the "Secure Boot mode" mode, erase all settings of this mode (first set the supervisor password) then turn off the "Secure Boot mode" and then try changing the boot mode.