Fixed! Bios resetting each reboot -- and it wasn't the CMOS battery A515-54-51DJ

gggirlgeek

Just wanted to post my solution for an elusive problem many seem to have in this forum:

My Aspire A515-54-51DJ would only run when plugged in. The battery wouldn't recharge — it was stuck at 83% according to Windows 10. After unplugging it and testing a different AC Adapter, suddenly, it wouldn't boot past the "No bootable device found" screen. I went into the BIOS and it had been reset, which is what caused the error message: My OS is set to AHCI mode, and also setup not to use Secure Boot, so the default BIOS settings are incompatible with the installed OS on my SSD. However, when I set the BIOS to my liking, and corrected the date and time, it would reset back to default again after I unplugged it.

Resetting the battery with a safety pin in the reset-hole did not work, and made the problem worse by also resetting the clock after every power loss. That was not happening before.

Now, I found it suspicious that both my internal battery, and my CMOS battery would fail at the same time. However, there wasn't a lazy way to test both without messing around with complicated voltmeter settings. A used, genuine, laptop battery, and a new CMOS battery cost me a total of $30 on ebay so I went ahead an ordered both.

When they arrived, I installed them, making sure to leave the CMOS battery disconnected for at least 5 minutes, and pressed the power button down for more than 30 seconds, just to be certain all residual settings from the old batteries were reset. I GOT THE SAME RESULT! ????

I looked around and noticed that my battery reset button on the motherboard didn't seem right. There was no mechanism to short it when a pin is inserted into the cover's whole above it. I suspect a part came loose that I hadn't noticed along the way. Just for giggles I decided to touch the metal part with the tip of a screw driver for a few seconds, with both batteries disconnected. I reconnected everything and then flipped it over and performed my BIOS-settings-dance. After saving the settings I unplugged the laptop, waited a few seconds and pressed the power button with the laptop unplugged (to see if the battery was working.) Voila! It powered on without an AC plug! I F2'd into the BIOS, and my settings were still saved — no reset. It was fixed!

To test if my old battery was still a problem, I plugged it in and, what do you know? The problem was back. I tested the old CMOS battery and it was still OK. So that was NOT the problem, even though the laptop acted like it was dead (BIOS resets the clock whenever all power sources are disconnected.) So there were 2 problems: The laptop battery was not accepting a charge anymore. Secondly, the battery-reset-button got stuck in a reset stage after I pressed it with a safety pin. It's possible it lost a part to short it when I removed the cover. Shorting it with a screw driver put it back into normal-mode!

I was not able to find the battery-reset-button fix, or any images of the lost part, by searching with Google, or in this forum, so I hope it helps others having this problem. I'll come back and post a picture of the reset button's current state if I can.

[Edited the thread to add model name to the title]

Puraw

https://community.acer.com/en/discussion/691568/fixed-bios-resetting-each-reboot-and-it-wasnt-the-cmos-battery-a515-54

Glad you got it sorted out, all you had to do was measuring the coin battery with a multimeter (3 VDC), available in any department store.

I have found that 4 years is the maximum you can get out of a a515-54G battery, much shorter if the battery was drained to almost zero. It is a delicate micro switch below that reset pinhole and broken switches have been reported on this forum, when the pin is misaligned or too much force is applied it is easy to damage the switch.

Great post.