|Your symptoms don't necessarily indicate it's overheating. |
It's NOT overheating if you get the symptoms first thing when you boot the computer after the laptop has had a chance to cool to room temp.
If it WERE overheating,
- if the cpu gets hot enough that it exceeds a certain max temp, the bios will shut off the mboard, and the laptop will NOT start up until it has cooled to below that max temp.
- if the cpu overheats but doesn't get to that max temp, the computer will probably "behave" erratically, but you do NOT lose the video if nothing else is wrong.
"When I switch on my toshiba laptop L455D-S5976 the cpu fan rotates shortly and stops ..."
That's not unusual for a laptop to do that. The fan often spins while booting or shortly after that, then it goes off until a temp has been exceeded inside the case, then it goes on again, cycling on and off as needed.
".....no display is seen at all ? "
Having no video on the built in display after the laptop has been used for years is a common problem.
Laptop no video (or video problems), and battery, AC adapter, power jack T shooting.
See response 1:
DO NOT plug in or unplug a monitor's video cable into / from a video port while the computer is running. Doing so can damage the monitor's circuits and/or the video adapter's circuits.
Some laptops will display on an external monitor without you having to do anything.
If you get no video on an external monitor, some laptops have a key combo that you must press to toggle the display to external video only / built in display video only / sometimes both - see the Owner's or User's manual for the model.
On Toshiba laptops you can toggle between internal and external screens using Fn+F5 keys. Hold down Fn and press on F5 until you get video on the external monitor.
If there is nothing wrong with your AC adapter or it's connection and the jack in the laptop.......
Laptop main batteries usually work as they should for a year or so, then they begin to rapidly deteriorate. From what I've seen, by two years they cannot be charged to anywhere near their full capacity, and it gets worse after that.
They often develop internal shorts when they are older. If the battery gets HOT rather than just warm after you have attempted to charge it for at least a half hour, or after you have been using the laptop for a while with the AC adapter plugged in, it's definitely internally shorted and you must replace it. Internally shorted batteries getting too hot have been known to cause the laptop to catch on fire.
Tips about battery charging problems on Dell laptops - may apply to other makes.
See response 3 in this by iTech: