Not booting

My machine was working fine when I packed it up 3 months ago. (We have moved) and I personally transported it (no movers) It has been in the box for that entire time and today I set it up. When I power it on, the green power light comes on as well as the HDD indicator. They both stay on and no signal is sent to the monitor. It doesn’t get into the BIOS. I tried pulling the memory sticks out and reseating them and still nothing. I have never encounterd anything of the like. Any suggestions? Please!!!