I have an Aspire V5-431P SNID [edited for privacy]. I wanted to boot from a CD in order to test my backup/restore procedure. I turned off secure boot in order to do this, and it worked fine. When I was finished I attempted to go into the Bios with F2 at the logo screen to turn secure boot back on. When I hit F2, the laptop beeped at me once and proceeded to boot up. I tried this several times, and even with a USB keyboard, all to no avail. I was finally able to get the bios into the state I needed by removing and reinstalling the bios battery.
I attempted to report this via chat, but the system could not validate my Serial number or my SNID.