|A cmos battery that is too weak or dead WILL NOT cause your computer to stop booting !|
They usually last at least 5 years.
Since it last worked properly, have you, or is it possible anyone else who has had physical access to this computer
- dropped it, or otherwise subjected it to a physical jolt ?
- spilled liquiid on it, or exposed it to liquid such as rain, or sprayed it with liquid ?
Has there been a power failure event, or lightning strikes in your region, since it last worked properly, while the AC adapter was plugged in ?
Any of those things is a lot more likely to cause damage to your computer that requires that something inside of it must be replaced.
Laptop no video (or video problems), and battery, AC adapter, power jack T shooting.
See response 1:
Some laptops will display on an extermal monitor without you having to do anything. Other laptops require that you press a key combo to toggle the display to external display / built in display - see the Owner's or User's manual for your specific model.
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: