Usually if there is no signal to the monitor, the computer also emits several beeps. Very common and relate to memory error, especially after delivery if badly handled or desktop been moved from one place to another or case hit/punched.
To solve we will suggest to open cover and remove all memory RAM sticks and clip it back again.
Please try the following steps:
1). Turn off the computer.
2). Unplug the power & remove the computer case.
3). The computer may have several memory slots, remove all memory, and switch slots.
4). Replace computer case and then reattach power plug.
5). Start computer
This should solve your issue.
If this does not work, please unplug the system from the power. On the back of the power supply there is a black reset button next to PS LED. Hold that down while the system is not connected to the power for 10 seconds.
Plug the power cable back on and restart the system.