Approaching my 73rd birthday (tomorrow August 12), I am keenly aware of aching joints. I had two computer failures this weekend; one was a desktop that declared "No operating system" and a laptop that reported a memory error. I've been at this game for a long time and often I pop open the case, blow out the case with a can of "DustOff", and gently massage the connections. No guarantees, but if it works, it is a cheap fix.
The desktop was a Dell Optiplex 780 SFF - slim form factor. It has a single thumb screw (I used a 6-in-1 screwdriver to gain access), pushed the hard disk drive connecter gently, closed up the case, reconnected the power and the system booted. The laptop, a Dell Precision M6400, was far more daunting. Memory goes bad, less commonly motherboards go bad, more often memory module to motherboard socket connections corrode. Manufacturers apply an almost molecule thin layer of gold. Massaging those joints requires access to the modules and sockets. In this laptop, two are underneath the keyboard and two underneath the base cover.
I found the modules with the assistance of a Google search. Pictures, detailed articles amongst a lot of noise. The bottom seemed easier to I started there by unplugging the brick and removing the battery. Electrical discharge can destroy circuits not to mention what they can do to your heart rhythm. The base cover is restrained by two small Phillips head machine screws. You can get by with a $1 set of "precision screwdrivers". Put them in a bowl in a secure place on the flat space you are working on. They can get lost in a shag carpet. I need a lot of light to do detailed work. I use a combination florescent-incandescent desk lamp but any lamp will do as long as it is bright and close. After two screws were removed, the base cover slid forward and came off, I used a magnifying loupe to find them,
The modules are restrained by clips on the side which when expanded allow the modules to lift up. At this point, I removed them partly and reinserted a few times, wiggling them into the socket and finally snapping them into place. Some articles suggest cleaning the gold fingers with an eraser. That works on copper but gold does not tarnish. Don't do it. I put the base cover back on, My fingers are not as nimble as they used to be so I use a hemostat which can be a little harder to find. Look in sporting goods, fishermen use them to retrieve hooks.
Turning it over and opening the case, I removed the "led" cover above the keyboard. A guitar pick or a small plastic knife makes a suitable tool. I disconnected the power switch cable and set the cover aside. I then found four screws, removed them and put them in the bowl out of reach of casual contact. This keyboard has the same sort of gold fingers and socket attachment. Most laptops have a ribbon cable which is fragile. I lifted the keyboard slightly and slid it backwards and set it to one side (which is why the bowl with the screws is out of reach). I repeated the same exercise as the bottom modules, reassembled the keyboard, reattached the power switch cable and put the led cover back in place.
After reinserting the battery and connecting the power supply, I turned it on and was pleasantly surprised to see it come to life. I wouldn't do this to a "newish" computer but on a five year old laptop, you have little to lose.