Question PC boot issues

[Mlouks6603]

When I turn on my PC there is one long beep and the USB mouse keyboard and monitor do not receive a signal.i have tested the USB ports with a cell phone charger and they do have power I have checked all of the cables and components everything is firmly plugged in and all fans and lights come on so my only guess is that after this computer was in storage a couple of years maybe the battery died?...... Any ideas or directions are much appreciated

 

[PC Tailor]

Please post your entire system spec including motherboard, and PSU make and model.