Fixed the lost key when quickly typing.

The upgrade procedure as below,
1. Installed AC adapter.
2. Please preparing a bootable utility disk and use it.
3. Decompress the ZIP file to this bootable disk.
4. Put the bootable disk into USB floppy, then boot
5. In DOS mode key in 'KBC' will start update.
6. After finishing, please restart the computer. Learn more.