What Are The Signs of RAM (Slot) Failure? I've recently attempted to install 2 sticks of 2GB RAM into my MacBook Pro, but unfortunately had jammed one stick in the lower RAM compartment (Apparently I forgot to enter it at 45°) and had a rough time getting it out. 

The RAM stick is busted and had to replace it, but I'm quite sure the slot might suffered a bit.

What are the signs of RAM failure?
A hosed slot (other than the obvious visual short circuit if the metal connectors are in contact with each other) will possibly cause the machine not to start. 

It can as well damage the memory stick (short circuit) when the computer is turned on with a stick in it. 

If the voltage mess is big enough, in theory it could damage more than that (i.e the board).

Electricity in electronics is very delicate and if the wrong current or voltage flows to the wrong place, bad things happen. 

Or… maybe nothing happens. Use a magnifier to see if the pins are aligned. If you see some in contact, it’s best to remove the battery and unplug the laptop and try to separate the pins that are in contact, even if you have to sacrifice the slot forever. 

Repairing that is probably expensive (800++ u$) because you need to change all the mother board.