Thank you for answering.
If the motherboard were fried, shouldn’t the power and hard drive leds on laptop case stay off at all?
The power led turns on and remains like that until I press the power button for second time.
The hard drive led turns on for a second, blinks quickly for another second, and finally turns off slowly like if it were a power failure. As I said, the power led and the keyboard and dell’s quickset backlights stay on until I “turn off” the laptop.
Again, thank you for answering.
Not necessarily - there are many possible faults that can lead to a no-boot, and they don't necessarily mean no power is getting to the board at all.
If you've tried a reset (unplug, remove battery and hold the power button 30 sec; reconnect the adapter and try to boot without the battery) already to no effect, the mainboard is bad.
If you have two modules, try one at a time. If one works in either socket but the other doesn't work in either, the module is bad.
If both modules fail in one socket, the socket is bad. You can either live with one module or replace the mainboard.
If neither module works in either socket, the mainboard is bad.