Question hp pavilion slimline s5000 wont turn on

[REX14RIFLE]

not really sure whats going on when i plug it in all the fans and the little green light on the psu turn on for a second then all that stays on is the power light saying that the whole machine is on. ive tried swapping out PSUs ram and reseating the plug and even clearing the cmos to no avail the computer was sitting in a garage for around a year and went through a deep cleaning with air and a soft makeup brush before i even attempted to turn it on i know the cpu is fine as well as the ram psu and hdd its using as ive tested them all on a separate machine.

 

[maxamillionfeettall]

Was the garage humid? I've lost a few motherboards having them sit for a while in a non-temp controlled garage before.