Continuous beeps at start up are usually due to POST problems. This is a very low level check of the basic hardware. The BIOS is checking that it has a working motherboard, CPU, Memory, keyboard, mouse, graphics card, monitor, hard drives, floppy drive.
The best way to check if any of these are faulty is to get a machine with compatible components and try swapping individual components. When doing this I first swap the keyboard out and try to boot, then replace the keyboard and try to boot with different CPU, then continue by trying a replacement for each item. Even a replacement battery is often worth a try as has been known to fix problems.
If, after this it still does not work, I replace eveything except the motherboard and try that, if this fails then the motherboard is usually stuffed.
BTW A low level format of a HDD is NOT possible with most modern systems, some of the older PCs with older BIOS have this capability but most dropped including it in the BIOS when the HDDs went over 10 GB as a low level format at home of a 10 GB drive would normally take several days. A bad or incomplete low level format can make the HDD unusable until properly completed.
The Format command in DOS or any other formatting system is a high level format only. Multiple high level formats usually will not cause any HDD problems. MBR repair etc is a high level format functions as well.
NB: Some proprietary systems (Dell, HP, Compaq etc) have some boot / BIOS and recovery image data on the HDD and a reformat whilst still in that machine will not always remove or replace this data unless a model specific utility from the manufacturer is used. You can blow this away by taking the HDD out and putting it in another PC and then use FDISK to remove ALL partitions and then recreat new partitions on the HDD, then format the partitions, and only then replace it in the original machine.