Battery light flashing amber

If the laptop battery is more than 3 - 4 years old then the battery could be worn out. Rechargeable batteries have a finite number of charge and discharge cycles and will lose their charge capacity over time, i.e. won't charge to 100% and gradually the charge reduces until the battery won't charge up at all. OR The battery shows a 100% charge but when the adapter is disconnected the battery drops off to zero capacity in a very short time. If the battery drops to an unacceptable charge level then the battery needs to be replaced. Rechargeable batteries will fail if stored in a discharged state for long periods.

Ok, lets start slowly, do you have both a new battery and a new battery charger? If both attempt to use your old battery with the new charger. Also could be a bad charger or a shorted out battery...
Good Luck

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.)

my power light flashes green/ amber as soon as it is plugged in, with a dead battery. It seems to go to steady amber if the plug is tapped, but goes back to flashing. It will not hold a charge on a new battery.

I had the same problem, I removed the bettery while it was still plugged in, tested it, then plugged it back and and now all is fine.
or you may try 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 - please look for a replacement. Hope it helps.

If the charge light shows a blinking amber, then the battery is dead. If the charge light shows a solid amber, then it's charging.

Which is it?

The cells in the battery are starting to go bad which is why the light is blinking the way it is.

Once you get a new battery put in there the light will stay blue instead of flashing amber.

LED indicator for your laptop model
Steady Blue = Battery charged and AC adapter plugged in
Amber = Battery charging and AC adapter plugged in
Slow Amber Flash = <10% battery life
Fast amber flash = 3% remaining TPC will automatically go into hibernate
Slow flashing amber Adapter plugged in = Overheat condition

Do you have a multimeter to test the battery that you are using? check the output current of 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


good luck