X200s dying when running on battery

[twistero]

My mom uses a ThinkPad X200s. After the original battery died, I bought her a third-party battery from battdepot.com, and set it to charge if below 60% and stop charging at 80%.
Everything was well for a few months, then recently the laptop started dying on battery power. Mom would unplug the computer, use it for a while, go do something else and return to see the computer completely powered down.
Today when she was using the laptop it died again, complete with the distinctive noise of the hard drive suddenly losing power. When I tried to turn it on, the battery indicator (orange) and plug indicator would blink once, then the battery, "Z" and HDD activity indicators lit up solid green as if the computer is starting normally. It then died a few seconds later. When plugged again in the machine started perfectly fine other than Windows complaining that it didn't shut down properly, and the battery indicator read something significantly more than 0% (didn't look at the actual percentage).

Now I do believe I have a failed battery on my hand, but just to be sure, is there some other known problem that may have these symptoms?

[AGoodSolution]

My mom uses a ThinkPad X200s. After the original battery died, I bought her a third-party battery from battdepot.com, and set it to charge if below 60% and stop charging at 80%.
Everything was well for a few months, then recently the laptop started dying on battery power. Mom would unplug the computer, use it for a while, go do something else and return to see the computer completely powered down.
Today when she was using the laptop it died again, complete with the distinctive noise of the hard drive suddenly losing power. When I tried to turn it on, the battery indicator (orange) and plug indicator would blink once, then the battery, "Z" and HDD activity indicators lit up solid green as if the computer is starting normally. It then died a few seconds later. When plugged again in the machine started perfectly fine other than Windows complaining that it didn't shut down properly, and the battery indicator read something significantly more than 0% (didn't look at the actual percentage).

Now I do believe I have a failed battery on my hand, but just to be sure, is there some other known problem that may have these symptoms?

Laptops can die if the CPU overheats and it kills the system to protect itself.
You're well served by using a can of compressed air and blasting the fan while the laptop is turned off.
Remove the keyboard and blast it from multiple angles.
You have numerous utiltiies to monitor temp and fan speed including venerable TPFancontrol.

Does the system have ThinkPad Power manager to delvier a status report on the batterys capacity, health and design capacity ?