I have a Compaq Presario 700 laptop which simply won't switch on, either by the mains or by battery; it's completely dead both ways.

Is the mainboard inside the laptop burnt out?

Could it be the charger board (I don't know exactly what that is - 've just heard of it!)?

Have you tried the old wiggle the connections thing. May be the board is fried but does anything come on. Power light etc

Try wiggling the connections. Try removing the battery and seeing if it boots on the charger. If neither work, then it time to take it to a tech.

If you are somewhat of a techie and confident, you could open up the laptop and remove and reseat the CPU. I have seen this simple operation cause a laptop to start again when it was dead in the water.