I hope whoever was poking around inside took precautions for static discharge (ESD). Anytime you muck around inside a computer, you can zap something unless precautions are taken. It's the same as when you feel a static spark except the voltage required to damage electronics is lower than you would feel. The RAM cards also need to be inserted carefully as the connectors are easily damaged. This idea that removing and reinstalling RAM will fix anything is a dangerous idea. I've never seen it work. You likely blew something on the motherboard or damaged the RAM. I suspect the former as even with the RAM not working you likely would see something on the display (an error message).