It took about 6 hours and a bunch of Russian-language websites to solve this one.
This is for people who have spent hours and hours trying to bring their dead or bricked Lenovos back to life after a failed BIOS update.
1. Get on a working computer and forget everything you read about making a bootable USB with Crisis tool, you don't need one.
2. Format your USB (16GB or smaller) to FAT32.
3. Download the latest BIOS from the Lenovo website. Currently that link is here:
https://pcsupport.lenovo.com/gb/en/products/laptops-and-netbooks/lenovo-g-series-laptops/lenovo-g580...
4. Now we're going to need to open Command Prompt. Hold Windows key+R, type "cmd", click OK.
5. Type without quotes in the box "cd C:\Users\<Your user folder name>\Downloads" and press Enter key
6. Then type without quotes "62cn97ww_32.exe /ext" and press enter (If your file has a different name, adjust accordingly)
7. You'll see about 4 files appear. The one you want will be called "62cn97ww_32.cap". Rename the .cap file to "BIOS.cap" and copy this file to your formatted USB stick.
8. Make sure your dead laptop is switched off. Plug in your USB stick into a USB 2.0 port (NOT the USB 3.0 ports). Hold down Fn+R, then while holding press the power key and keep it held down untiil something happens.
If successful, your laptop screen will light up, a DOS screen will appear and the BIOS will flash itself. If it doesn't work, the laptop will immediately switch itself off again. Leave this running until it's all done.
I hope this helps someone googling this in the distant future.
Keywords you might have searched: QIWB5.bi? / QIWB5.bin / phlash16.exe / Crisis tool / WiNCrisis / boot.wph
