extended 'no-start' any issues on laptop?

does not booting the laptop for a while could cause any issues? (don't think so, but i will tell the story more below)..

the sony monitor was broken.. when we booted we can see some part of the monitor, others were dark patches as evidence for the damaage... other than that, all other features worked (CD/Audio/Video to S drive, wireless etc). so we thought it was wise to change the monitor and get it going.

so we ordered a new one and came after a delay.. meanhile, without shutting down, we just closed the laptop lid and put it in a corner. By the time the new monitor came, assuming all the battery is gone, we just took off the monitor, and put the new one, and started again.. but now there is no life on the monitor.. we thought it may be the new monitor.. so we took it off and put the old one.. still the same..

the power and batter indicator is on.. but there is no HDD indicator (VGN 220E).. so now wondering somehow if the power supply or motherboard could have damaged when I was turning the laptop around etc.

one mistake is i should have started the laptop to make sure it is working before putting on the new monitor.. now, i don't know if something broke between the time the laptop was in the corner (no one could have touched.. so possibility of physical damage there) and the new monitor was put in..

any thought how i can troubleshoot this?

the laptop is 4 years old and well used. (used in lot of car and air travels)

when the power button is on, the caps lock does not turn green, so i suspect the HDD/OS is not turning on..