Dell latitude D600 battery charge light flashing

My Dell laptop's battery used to work properly and charge and show a green light flashing while charging. Now I can't get the battery to charge and when it is plugged in I am seeing the charge light flash orange quickly 4 times, followed 1 longer green light flash.

The computer appears to work fine while plugged, but won't work when it is not "plugged in".

1. ***IT ALL DEPENDS WHEN YOU REMOVE AND REINSERT THE BATTERY***
   
   The diagnostic procedures from the Dell User Guide are as follows:
   
   Total Power Failure When Using a Battery
   If an AC adapter is not connected to your computer, the computer's power source
   is a battery. If the battery indicator flashes amber or is a steady amber, the
   battery needs to be charged. If the battery is flashing green and amber, the
   battery may be defective. To troubleshoot this problem, use the following
   procedure.
   1. Turn off the computer and peripherals, and disconnect them from AC power.
   2. Reseat each installed battery by removing it and then replacing it.
   3. Turn on the computer. Does the green power indicator light up?
   Allow one minute for the computer to initialize its components before checking
   for signs of power.
   Yes. Continue to step 4.
   No. Use the AC adapter to connect your computer to AC power. If the computer
   operates normally when using AC power, go to step 7. If the computer does not
   boot when using the AC adapter, see the previous subsection, "Total Power
   Failure When Using the AC Adapter."
   4. Does the battery indicator flash amber or show a a steady amber light?
   Yes. The battery needs to be charged. Go step 5.
   No. Go to step 7.
   5. Connect the computer to AC power, and fully charge the battery.
   For instructions, see the topic titled "Charging the Battery" in the online
   System User's Guide.
   6. As the battery charges, does the green battery indicator light up?
   Yes. Go to step 9.
   No. Go to step 7.
   7. Is the battery indicator flashing green and amber?
   Yes. Your computer may be in a hot environment. Charging the battery in this
   condition may affect the life span of the battery. Continue to step 8.
   No. The problem is resolved.
   8. Disconnect the computer from AC power. Is the the battery indicator still
   flashing amber?
   Yes. You may have a defective battery. Continue to step 9.
   No. The problem is resolved.
   9. Remove the battery, and press its test button. Is the uppermost indicator in
   the charge gauge of the battery flashing?
   Yes. You have a defective battery. Continue to step 9.
   No. The problem is resolved.
   10. If a spare battery is available, fully charge it, and then install it in the
   computer.
   11. Turn on the computer. Is the power indicator off?
   Yes. Your original battery is defective. Call Dell for a replacement. (See
   Chapter 5, "Getting Help," for
   instructions.)
   No. Call Dell for technical assistance. (See Chapter 5, "Getting Help," for
   instructions.)