That flash code means you have a problem with the battery. It may need replacing. If it won't hold a charge, that's how you'll know. These Li-On batteries don't last forever, and when they go, they go! So they have a built in safety circuit that monitors the battery state, the number of charge/discharge cycles, etc, and when it decides it's time to quit, it won't let you charge it any more. Time to send the battery for recycling and buy a new one, or take it out and just use the laptop on AC.
This illustrates the Three Rules of Contrex:-
1. Don't buy a Dell.
2. Don't buy a laptop.
3. Don't buy a Dell laptop!!!!