Trying to install OS

Hey all. After sucessfully installing Manjaro on an (arm) Rock64, I liked it so much I thought I’d try replacing Ubuntu on an older IBM Thinkpad T500. I downloaded 2 different Iso’s, Cinnamon, and Plasma. I burned both to DVD’S using a Windows 10 Lenovo Ideapad. When I tried to boot from the DVD, on the Ideapad it just sat there wheels spinning. Taking the DVD out of the drive, it boots to Ubuntu via the hard drive. I then tried a usb DVD drive with the same results. (setting the boot sequence priority as needed) still nothing. Since the instructions stated I could boot and run beside the host OS, I decided to try booting on the Ideapad, (it’s quite a bit newer than the Thinkpad) The drive spun up, and a pop-up error appeared saying "Image failed to verify with SECURITY VIOLATION ". I’m not sure where to go now…Thanks in advance for any help

Disable Secure Boot. It’s not secure, anyway.