In my opinion, the reason that you are unable to boot your laptop is the fact that the motherboard
battery of the laptop got exhausted and needs either replacement or reset. Have you tried resetting it? If not, please try то do so. If you don't have new CMOS
battery, you can just take the current one for some minutes and wait to discharge. You must do that after you have pulled out the battery and the power cord of the laptop. Open the lid and localize the CMOS battery which lies next to the processor
and it looks like a watch battery. If you have another CMOS battery, you can replace it with that. If you don't, leave your current battery aside and wait for some minutes for the electricity to discharge. Then, plug the CMOS battery back in and the power cord. Try to boot your laptop again and come back to the topic to tell me what happened.