Fixing a dead Laptop

I often have people ask me to help with a dead computer. So here is what I do to get one back running.
The symptoms are: it powers on, but just sits there, power light on but no noise, no screen, no beeps.
Used to be computers used beep codes if there was an error at this time, but not all do anymore. If it was beeping I would look up the beep code (on the internet) and see what the problem is. But not all computers beep now so not beeping may or may not be a bad thing.
First try the obvious and easiest things.
Try the power off/ power on. If a simple press of the power button will not turn it on or off then press and hold for 10 seconds for it to over-ride and power on/off. Remove the battery and power cord and try an on off cycle to clear any residual charge then plug the battery
Now try to see if it is just trying to use the secondary video for output and is stuck at the cmos prompt. Press and hold the fn key and press the f8, f5 or f4 key to switch video modes (try them all if you don’t know what is correct for your system.)
Try getting into the cmos using del or f2 or f12 keys. This may wake your system up. Power off, power on, start clicking the setup key. If it works it may take a few seconds.
Now try other keys and key combinations like esc, break, ctrl-alt-del, whatever, just to be sure and because it’s easy and who knows might work.
In a working laptop, when it starts (any computer) it follows a sequence (the POST); it starts off by first checking the cpu is good, that the first 64k of memory is there and the video is working at minimum levels. Then it starts up the video and prompts for if you want to enter setup. Then opens the bios code, and gets the details from the bios for the memory hard drive and other peripherals, then starts to check those to see if they are there and working. Once it finds everything and all is OK it loads the OS from the hard drive or other boot device.
In this case the power light is on so the cpu is at least trying to start. Power keys now a-days are not really power keys they switch a set of pins on the motherboard to tell the computer to start, then the MB puts the power to the cpu on but if that check doesn’t work the power light goes back off.
This laptop is stopping before it even starts to try the video. SO there is an issue with either the cpu not working/not seated properly, or the first 64 k of ram is not available (may need to be reseated) or the video is bad (if so probably the video chip as it is not able to check the actual display yet.) It hasn’t gotten to the front-side or back-side bus yet so those things and the devices on them can be ignored for now.
I have one system that won’t power on with the first cycle of the on/off switch. It tries to start, but then quits. If the system were off for any length of time say five minutes you have to hold the power key down while it cycles and cycles for up to 30 minutes for the system to start. I never shut it off and it has batteries so survives most power outages. But when it does get shut off it is a pain to restart.
(From this point on it’s best if the person doing this has some experience with electronics and computer assembly/safe practices.)
Then I would reseat the memory if it is easily accessible. Memory in laptops and computers can develop issues with the connections of the simm/dimm and the slot; so reseating it tends to clean the connection enough to make the memory work again. This will fix probably 30% of not booting machines.
The next thing is that the bios settings may be scrambled so remove the cmos battery for 10 minutes for the cmos to completely reset. This is drastic as you will have to do a complete reset of the cmos settings when you do reboot, but with most modern pcs and laptops you don’t need to know the exact settings for things as there is a factory reset and most of the devices are easily detectable for auto resets.
If that doesn’t work or it’s not easily accessible you are getting into now having to start disassembling the laptop and while that is a fun and strangely satisfying thing to do don’t do it unless you are experienced and competent enough to reassemble it again. I try limiting myself to disassembling a laptop to one a week as it’s more costly to pay me to do this than it is to buy 4 new laptops.
SO after taking the laptop apart I would reseat the cpu (unless it is one of the soldered on ones in which case, um, not reseat it), check and clean every connection of cables, chips, dimms and peripherals.
I would start pulling out my diagnostic tools now, things like a good multimeter work but we have everything from oscilloscopes to cmos programmers at work so I would be doing things like testing the cmos and reading the data on it and comparing that to what should be there. Check the voltage of the cpu power connector (you would need the motherboard schematics) and look for burnt/missing capacitors and resistors. Sniffing, if you have a good nose can tell you if there is a burnt out component. Usually now a-days it’s easier and cheaper to replace components than to fix them so I tend to do fixes at the component level now only as teaching aids or for fun after hours.
I know most of this is not very helpful unless you have the tools and confidence to rip apart your laptop, and I hope your laptop can be easily fixed by the memory reseat or rset of the cmos or you can find someone close who will freely give you the time to do a tear down and fix it but in most likelihood you are having to buy a new laptop.
If you do decide to replace it, don’t throw it out. If you are inclined to play with electronics, or have a friend who is, first remember to transfer the data from the hard drive to your new laptop (you can get an adapter case to make it an external drive or get a computer friend or store to do the transfer for you) then get the manuals for the laptop off of the internet and tear the thing apart to see how it works.
OR you could sell it non-working on ebay to someone for parts, or even go to a computer recyclers and see if they need the parts and they may pay you for it. You may also find a nice used replacement for it there as well, but their stock goes fast for good stuff.


About echlinm

Computer Programmer/Systems Analyst/Hacker S31
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