Power AND Battery lights on HP Laptop start flashing

This is another undocumented "feature", found on recent Hewlett Packard laptops. According to the light codes found on HP's website, it is not possible for both lights to be flashing, but you have found this page, obviously it is happening on your laptop!

What is occurring is a "retraining" of the battery. Laptop batteries naturally lose their capacity over time, and some HP laptop BIOS are set up to "retrain" the battery at various times, in an attempt to regain some of that lost charging capacity. Once the process is initiated, the battery will be charged to 100%: at this point, both the power and charging lights will flash briefly, and then the battery will begin to discharge.Windows will shut down once the battery reaches 5% (the default power setting), and the discharge will continue until the battery is at 0% charge.

However, the BIOS will be confused if the charger is still plugged in! If the charger is plugged in when the "retraining" is happening, the battery will never reach 0% charge. Even if you unplug the charger, it could take years for the battery to naturally discharge, and if try to power on the computer, the BIOS will re-initiate the "retraining" (i.e. charge to 100%, and then discharge).

The sad truth is that there is no way (that I have found) to disable this "retraining" option. The only real option I had was to replace the battery, which I did. The new battery worked flawlessly, and I have not seen the laptop attempt to "retrain" the new recruit.