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Repair guides and support for the laptop line of Acer's Extensa series for office and business use.

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Acer Extensa 4420 Computer not booting + LCD problems

I recently purchased this device at a garage sale for a grand total of $3. It is an older Vista laptop, and I mainly purchased it for tinkering and messing around with it. However, it's got me stumped with its booting problem. When I press the power button (see attached video), the drives spin up, the power light comes on, fan spins for a second, and the drive light blinks. Then, after a few seconds, everything goes dark, before coming back up and doing the whole thing a second time. The LCD shows absolutely no signs of life.

Things I've tried:

Plugging in an external monitor

Booting without the hard drive

Using each of the two sticks of RAM individually

Booting with only battery and only power cable

Repasting the CPU + cleaning out 15 years worth of dust

Shining a flashlight on the display (in case backlight wasn't working)

Booting with a boot DVD in the DVD drive

Booting without the DVD drive

Booting without RAM

Booting with only known good RAM

I successfully transplanted both the RAM and HDD into another working laptop and everything worked spectacularly. The hard drive appeared to have a corrupted copy of Vista installed; it would boot a "Windows failed to start" screen and both the "Start normally" and "Repair installation" options resulted in a blue screen. I installed Ubuntu on the drive and the install performed without any errors. Both sticks of RAM are recognized and have the correct values.

Also, I noticed the LCD has some dark pixels (see attached photo), even though it's not getting power. I'm not sure if this is a sign of a destroyed LCD or just a minor problem. If it wasn't for the powering problem, I would guess the LCD was just bad.

I'm kind of at my wit's end here. I don't know if the issue has something to do with the motherboard, the CPU (although I've heard that's pretty rare), or something else. Any help would be greatly appreciated!

If you need any more information, just ask!

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Hi @fixer85785

Couldn't see that you tried it in your question, but try replacing the RTC (Real Time Clock - aka cmos) battery on the motherboard. Given it's age it has probably failed.

It's a non rechargeable, 3V DC Lithium CR2032 coin cell battery, available most everywhere e.g. supermarkets. If it is <2.6V DC or >4-5 years old, replace it. The battery model is stamped on the battery if you wish to verify.

Removing the RTC battery (as well as disconnecting/removing the main battery) and holding the power button operated for 30 seconds resets the BIOS back to its default condition. This procedure is done when corrupted BIOS software prevents the laptop from starting properly. A corrupted BIOS is usually caused by a low RTC battery as the RTC battery maintains the BIOS when the laptop is turned off.

Given the location of the battery in your laptop is on the underside of the motherboard, pressing the power button is not required, because you would have had to remove the motherboard from the case to access the battery. By the time you checked the battery's voltage, out of circuit and inserted a new replacement battery, a BIOS reset would have occurred.

If the laptop does start OK it will show the incorrect date and time as the BIOS has been reset back to default. Once corrected it will maintain the correct date and time.

Here's a video that shows how they tried removing it without removing the motherboard but I don't think that it worked as the board had to be removed anyway. Too dangerous to try this, in my view, even if the main battery was disconnected, as damage to the motherboard could occur using the probe.

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Ok. Thanks! I always thought the CMOS battery was just to keep track of date/time and a few odd BIOS settings. i.e., important and useful, but not mission-critical and enough to stop the machine from booting. Is that true or just a silly misconception of mine?

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That worked! After an extremely arduous disassembly and reassembly, it booted right up (on an external monitor)! Now all have to do is deal with the dead backlight and broken hinge...

I guess you get what you pay for!

Thank you so much for your help!

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@fixer85785

To my knowledge it maintains the D&T and also all the user definable BIOS settings and it also provides the initial power to the Power button to start the whole startup procedure.

However and this is just what I think, if the settings are corrupted and therefore not able to be "read" by the BIOS then it stops because it doesn't know how to proceed.

Here's a download for the schematic ( only one that I could find - costs more than the laptop??) which may help if the backlight problem is not in the display assembly.

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Ok. Thank you so much!

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