50% of all computer problems are connection issues. More so if the computer has been transported. Constant beep sounds like a hardware problem.
Open the machine and remove and reattach every cable and connector you can find, including the CPU card if yours is one of the models with a processor on a card. including the drive cables (both ends) and also remove and re-seat the RAM.
Inspect the machine for any signs of cracks, damage, or components having come adrift inside the machine. (I once had UPS drop a computer so hard that the hard drive cage ripped off and caromed around insidde the case like a pinball)
Then do the power management reset as described above. If your machine is >4 years old it may also be time for a new PRAM battery (good investment of $10)
Double check to see that the voltage switch on your power supply (should be right near where the AC plug goes in) is set positively to the correct voltage for your location.
Thanks
Trevor
CanadaRAM.com