Ok , I've checked this, and the UEFI BIOS clock didn't reset, nor any of the settings.
Looks like the battery is fine, but the system still beeps at around 50% of power-on events.
I'm gonna try and contact ASUS tech support about this.
My PC recently is making very strange, elaborate beeps before post shows up.
I'd describe the sequence as as:
long + short + pause + medium + short
Here's a recording of the beeps:
View: https://youtu.be/j0DL2txUiTY
I've been looking for some information what could they mean - but I didn't...