1, maybe the bios has been changed, so that the motherboard does not accept some form of support.

2. The battery may be broken or dead, so the computer can't be turned on when it is plugged in. In addition, plug in the battery and plug in the power cord, and the machine cannot be started. It may be that the internal configuration of the motherboard is: when inserting the battery and the power cord at the same time, the battery is the first choice, but the battery is broken and cannot be started.

3. But when the battery is not plugged in, it can only be turned on when the power cord is plugged in. Because the motherboard can't detect the battery, it can only be turned on normally. Take it to a special store and replace it with other batteries to see if it can be turned on. If you can, prove that the battery is broken.