Dell Inspirion 3721 will not boot beeping repeatedly

Dell Inspirion 3721
Dell Inspirion 3721
Dell Inspirion 3721

The situation

So. in this case it was an Dell Inspirion 3721 laptop, which after having upgraded from Windows 7 to Windows 10, would from time to time get in some sort of sleep mode in which it would power off, and when you would like to power it on it would just started beeping every second or so. I will find a video on youtube showing exactly what would happen. Also, the screen would remain blank, and laptop wouldn’t respond to any kind of command.

As this was happening every 10 to 20 days, the owner didn’t put much effort on tracking down the error, because he would simply hold down the power button until it would turn off, let it sit for 10 seconds and boot it up with no problem at all.

Last week, after this happened again, the laptop wouldn’t turn on anymore…

What we tried…

We tried the usual steps to try and “wake ti up”, but it didn’t budge – as soon as the laptop would start up, there was a blank screen, you could hear the CPU fan start up, shut down and the beeping would start.

First we tried without the battery – same result. Then we tried removing the battery and AC power, holding down the power button for 60 seconds, reattaching the AC power – same result.

Tried swapping out the RAM modules, HDD drive and even the WiFi card – still the result was the same.

Dell Inspirion 3721 back
Dell Inspirion 3721 back

How we fixed it:

I was already looking for a replacement board, but wanted to try a few more tricks. So here is what I did to wake it up, and hopefully resolve the issue:

1. Turned the machine off

2. Disconnected the AC power and battery for the laptop, as well as the CR2032 BIOS battery.

3. Let it sit overnight.

4. In the morning, before i started reassembly of the machine, i measured the voltage of the BIOS battery, and it was around 2.95 volts, so I replaced it with a new one.

5. Reassemble the laptop, leaving out only the laptop battery and attaching the AC power.

6. Power up the machine – and it worked, the computer booted up to Windows without any problems.

7. Then I went to the Dell support site and saw there is a BIOS upgrade (A16 version, from 23 November 2018) which i was 100% was a newer version that was on the laptop. So i downloaded the BIOS update, started the program and it showed that it has the A05 version on it! This was clearly an very old version, and i went for the upgrade right away! The process was very user-friendly, with many usual warnings (don’t disconect the power or battery, don’t turn computer off….) it did it’s thing, rebooted once and it was all done. I started once again the program just to make sure of the version and it showed it is the latest, A16 BIOS version.


If you have a Dell Inspirion 3521/3721/5521/5721 or Vostro 2521 and have upgraded to Windows 10, or are having problems with intermitent beeping/not booting give this method a try!

The links:

Link to the Dell US site with BIOS update is here

The link to a Youtube video of a Dell laptop doing the same beeping sound is here

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