I encountered this problem and was lucky to find the solution on this forum. To help others, I am making this new post with more detailed info.
Problem: you wish to update the BIOS (for whatever reason). You either do not have a CD-Rom (disc drive) in your machine, or it is not working.
Solution: locate an external disc drive, or better: install (even if only temporary) a CD/DVD drive: there are lots available for free from anyone who deals with computers.
Reasoning: the "flash using Windows" method is risky. I used it, because the drive that came with a "new"(used) computer was inop., and I didn't want to stop, find one and swap it out. The BIOS flash routine failed before completion and therefore did not initiate a re-boot. The end result was that the computer would start, but hang after the BIOS loaded and went to boot the OS. No method of starting would work. {Described in this post: https://forums.lenovo.com/t5/ThinkCentre-A-E-M-S-Series/M92p-no-longer-booting-after-BIOS-update/td-p/3334060 }
Rant: the text file detailing the "Flash with Windows" utility should include a specific warning that flashing within an OS is inherently _RISKY_! It should strongly recommend using the "make a CD-rom disc" method. Furthermore, the instructions for recovery from the Hardware Maintenance Manual SHOULD BE INCLUDED!:
My compliments to the technical staff that created the CD-rom BIOS recovery program. It is "brain-dead" easy to use. Unfortunately, brain-dead management does not recognize the value and put it _Up Front & Center_.
Recovering from a POST/BIOS update failure: {from HMM}
If the power to your computer is interrupted while the POST and BIOS is being updated, your computer
might not restart correctly. If this happens, perform the following procedure to recover from the POST and
BIOS update failure. This procedure is commonly called Boot-block Recovery.
1. Remove all media from the drives and turn off all attached devices and the computer. Then, disconnect
all power cords from electrical outlets and disconnect all cables that are connected to the computer.
2. Remove the computer cover.
3. Locate the Clear CMOS /Recovery jumper on the system board. See “Locating parts on the system
board” on page 75.
4. Remove any cables that impede access to the Clear CMOS /Recovery jumper.
5. Move the jumper from the standard position (pin 1 and pin 2) to the maintenance position (pin 2 and
pin 3).
6. Reconnect any cables that were disconnected and reinstall the PCI card if removed.
7. Reinstall the computer cover and reconnect the power cords for the computer and monitor to electrical
outlets.
8. Turn on the computer and then insert the POST and BIOS update (?ash update) disc into the optical
drive. Wait a few minutes. Then, the recovery session begins. The recovery session will take two to
three minutes. During this time, a warning message will be displayed and no action is needed from you.
9. After the recovery session is completed, there will be no video, and your computer will automatically
turn off.
10. Repeat step 1 through step 4.
11. Move the Clear CMOS /Recovery jumper back to the standard position (pin 1 and pin 2).
12. Reconnect any cables that were disconnected and reinstall the PCI card if removed.
13. Reinstall the computer cover and reconnect any cables that were disconnected.
14. Turn on the computer to restart the operating system.
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Mod: edited Subject line to add "ThinkCentre" and expand description