There was no beep when I installed rc2 either, just wait until the disk
stops spinning and hit s and enter and you should be good to go. The
beep comes and goes through versioning changes.
This doesn't help, unfortunately, if the USB drive referred to turns out to be
a flash memory device, which obviously doesn't spin.
If the UEFI or BIOS in the machine doesn't beep, it's even worse.
There is a real need for accessibility at the firmware level. Most systems
lack support for IPMI or serial console.