This should be posted in the laptop forum but it could be the coin cell battery if the voltage is low that can cause all sorts of strange issues.

Replacing the battery is not simple the motherboard needs to be removed. So first use the built in diag the check the laptop by:

Hold down the key while pressing the power button or

Turn on the system, press at the initial Dell™ logo screen, and select Diagnostics from the boot menu.

Make a note of any issues then call Dell support.