Well the RAM can cause problems booting when it´s not properly placed on the slots, or there is damaged RAM or slots. Steps to troubleshoot:
Option 1 (I saw you have 4 slots and don´t know how many sticks, I´ll just assume is 2):
1. Remove both sticks
2. Place only one in slot n°1
3. Try to boot
4. Repeat the process placing the RAM on all 3 remaining slots and try to boot every time.
5. Repeat the process with the 2nd stick.
If the problem persists, then it´s not the RAM, unless all slots are damaged and all DIMMS are damaged, which wouldn´t be surprising knowing how you got your hands on that thing.
Option 2 (The HDD, some HDDs are damaged by liquid and prevent boot):
1.Just remove the drive and see if it boots.
If everything fails look for signs of liquid damage on the motherboard (It´s pretty obvious, it looks like fungus or some crap).
You should also try cleaning fans and applying thermal paste (I wouldn´t do it, since you are not sure and you´d have to spend 4-5 dollars on that, waaaaaaaay more than you should actually use on that... thing).