Changed from RST to AHCI system wouldn't boot

When I was installing Linux Mint, I got a message saying to turn off the RST.
I turned it off by changing ti to AHCI from the BIOS and now I can’t boot from the flash drive.
The system kept saying “Preparing Automatic Restart”.

It won’t reboot from the flash drive.
Does any one have any ideas why?

How can I fix this to have the system look for the flash drive and boot from it?