Dewalt battery charger flashing fast not chargeing

some batteries are bad from factory, you should exchange it for another and try again. Make sure the battery voltage and type (ie. lithium, Nickel Cadmium,etc.) match the charger. If not, you can buy most replacement batteries for older models on the internet. If a second battery doesn't work - it's the charger .

If this is a newer purchase, my newer Milwaukee flashes slow for the first two beats and then quickly while it reads the battery type and then shifts to the slow flashing charge light after it determines the type. this is because it is a smart-charger and can charge different types of batteries

Yes normally means faulty battery pack try another one

On some chargers, when the light blinks rapidly, it means that the battery is bad. Try looking up charger information on-line.

I believe the battery can no longer be charged.

Some battery can not be charged by fast charger, because this can damage the battery. You can think to replace it to a new charger, a 7.2V 9.6V 12V 14.4V 18V NI-CD NI-MH BATTERY charger for Dewalt

IF is doing that without battery on it maybe charger is bad but if flashing that way when you put the battery could be the battery hope this helps!

This means there is a "pack condition" and the charger believes the battery is bad.

If you look on the charger there should be a flashing codes should be explained depending on the type of flashes. Very fast flashes, means bad battery.

it doesn't change to green, the solid red light means it is fully charged, there should be a legend on the front of the charger to help you with this. If it flashes real fast the battery is malfunctioning and slow flashing is charging and again solid is fully charger.

could be a fuse in the radio. check with your local dewalt dealer.