Usually, "one beep" means that the POST (Power On Self Test) has completed, without incident.
Put in a new CMOS battery.
Borrow/purchase a USB keyboard.
Use the keyboard to enter BIOS SETUP.
Reset the date/time, and ensure that the disk-drive is listed as an eligible "bootable" device.
Save/Exit from BIOS SETUP.
It should now boot from the disk-drive.