guys pls help firmware udpate nightmare.

Reboot and Select proper Boot device
or Insert Boot Media in selected Boot device and press a key
No bootable device -- insert boot disk and press any key
i was updating the desktops BIOS using teh Mac OS X Lion Update for MacBook Air and Mac Mini 2011 package from Apple. then the progress bar froze. since then, black screen. im reasonably technical but Ive never had to recvoer a BIOS 😂 is this repairable at home? the keyboard lights flash briefly when i press power, then nothing. i have another computer available to download files and prepare a USB stick if a recovery procedure needs it. i just dont want to make things worse by guessing. seriously need help here 😭