You will need to open the laptop to fix this..

inside in laptop is a small c-mos battery, this needs needs to disconnected for about 10 minutes with the main battery disconnected and not plugged in.

replace the battery and the back of the laptop, and boot it up.

after unplugging the battery and mains press power button to release any power left in the system then take the battery out or replace, but this has worked for me 100%