First time ever posting on a forum but all posts above are accurate and I'm a novice with working on and repairing laptops, meaning I've never done it before.
Over the last several weeks my Vostro 1310 system occationally would not boot up and Blinking 9 and Blinking A and steady Down Arrow would occur with black screen - next try it would boot. Now, system does not boot at all. I put in a new Hard Drive and planned to try a complete reinstall (first time ever) but same problem with blinking lights and system not booting.
Then I read this forum, put original Hard Drive back in, took out one RAM and blinking lights stopped but no boot. Took the other RAM out and put it in the first slot (leaving the second slot empty). System booted up right away. Simple solution, fixed the problem in 5-minutes!!
This problem with Blinking 9 and Blinking A and steady Down Arrow IS NOT a problem with BIOS, the battery, the Mother Board, or the CPU as other forums may have suggested. This is a simple failure of RAM that anyone can fix - don't be afraid, just do it.
Good luck!