Wednesday, July 23, 2014

How to Recover a Laptop After a Failed BIOS Update

Introduction

A few days ago I managed to brick my Compaq Mini 311 netbook by mistakenly flashing the wrong BIOS image. The computer only switched on the CPU fan for a moment when I pressed the Power on button, then it switched off, nothing worked, no lights were on.

Since the netbook was working perfectly well before the BIOS update I immediately knew that the wrong BIOS image was at fault. However, flashing the correct image required the netbook to start up correctly in some kind of an operating system, which, without a proper BIOS, is not possible. Not even the Win+B combination worked.

Luckily, not all is lost, as all it needed was a correct BIOS, which I could easily download from the manufacturer's web site.

Yes, it's a Compaq Mini 311 netbook. I prepared a replacement chip loaded with the correct BIOS. Later it turned out that the original chip was not destroyed by the procedure I put it through.


Once I had to open the laptop to fix it I decided to take this opportunity to explore the options there are for fixing the broken BIOS and compile my findings in this article. In the process I tried all of the methods described below, some on the actual laptop I fixed eventually, some on (really-really) dead motherboards.

There are several ways of getting the right BIOS back in the computer - in the following I am going to present a number of ways to get your laptop back on its feet. There are probably more ways to do it, but this should be a good starting point for someone in the same shoes as I was.

General information

Most fairly recent laptops have their BIOS in a serial EEPROM with an SPI interface on the motherboard. Its location varies, but since it is the only EEPROM on the motherboard, after a few minutes of visual inspection it is easy to reveal it. In some laptops it's covered by a black sticky tape which needs to be removed temporarily to get access to the chip. These EEPROMS are usually 1024kB (1MB) or 2048kB(2MB) in size. They come from various chip manufacturers, like Winbond, STM, Microship, etc. Not to confuse with BIOS (firmware) manufacturers, i.e. Phoenix, AMI, Award, etc. The product number is printed on the chip and is something like this: 25xx80 (1MB) or 25xx160 (2MB). There may be some extra letters in the front or at the end that are all important when you select a replacement chip, but for the purpose of finding the chip on the motherboard they are not relevant.