7.1. The Moment of Truth

Your system's first boot on its own power is what electrical engineers call the “smoke test”.

If you are booting directly into Debian, and the system doesn't start up, either use your original installation boot media, or insert the custom boot floppy if you have one, and reset your system. This way, you will probably need to add some boot arguments like root=root, where root is your root partition, such as /dev/sda1.