Your symptoms and errors are very common when the 3v battery on the motherboard is weak or dead.
The good news is that these batteries are cheap and can be purchased almost anywhere. It is usually a CR2032.
After replacing the battery you will want to perform a Clear CMOS (or CLRTC) to reset the BIOS. That is done like so:
- Note all your current BIOS settings
- Shut down the computer > remove the power cord.
- Remove the 3v battery.
- Move the CLRTC jumper from pins 1-2 to 2-3.
- Touch a metal part of the case and Press and Hold the reset button for approx. 30 seconds to discharge all power from the board.
- Put the CLRTC jumper back on pins 1-2.
- Replace the 3v battery > replace the power cord > boot.
- Immediately go back into BIOS and reset all your preferred settings. If the CLRTC worked you will need to reset the date and time.
Some modern PC motherboards have a RESET button on them to perform the BIOS reset, but I believe the a6305 is not that new.
As I've said, if you are uncomfortable inside a computer case, or can't find the CLRTC jumpers, then it makes sense to take it to a shop or find someone you know who knows how to do this procedure. It is a very simple procedure and will take no more than 15 minutes. They should be able to do it while you wait for a minimal charge.