the problem is the battery always keeps around 99% power, would it be the problem that  power adapter  is insufficient? Here’s the repair process:
1) Connect the old battery and external power supply—laptop could work;
2) Connect the old battery without external power supply—2 seconds later after starting, the laptop shuts down;
3) Pull out the old battery and connect external power supply—the laptop could work;
Remove the old battery, and check up the battery slot carefully, check and compare the laptop battery connection joint, and find that everything is OK. Then it would be the problem of the battery or power supply circuitry. Change a big power adapter about 90W to 120W, and charge for about 3 hours. But the power still shows 99%. Now change a new battery and star the laptop. It could work normally now.
Prompt: actually even you don’t start the laptop, the battery would still charge. And at this moment, even BIOS is not running. Generally, our laptop has some software (such as BatteryMon), which could test laptop battery. While laptop could only query battery power, it doesn’t have the function to test. So usually, users may mix up these conceptions. Radically speaking, the power marks 99%, but it could not prove the laptop battery has no problem at all.