I have an HP Probook 4420s (yeah it is ancient). I recently replaced its internal HDD with an SSD and its DVD drive with an HDD in a caddy. It was functioning well no problems there. I had disabled its optical drive bay temporarily since the HDD in the caddy already had an installation of Windows and I did not want it to interfere with the new installation. I dual installed Windows 10 and a Linux distro (Manjaro to be specific) on the SSD with GUID partitioning running on UEFI. Now I want to enable the optical drive again, but was unable to do so. I realized that the BIOS was not saving the settings anymore. I tried to change various settings, even tried the reset option, but to no avail. I might as well add that trying to set an administrator password on the BIOS works.
Is there a way to diagnose if my BIOS is working (reading/writing) properly?
Update: I tried changing the battery, but it still isn't working.