How to access BIOS using an HDMI cable?

Look, I realize the title is a bit of a mess, so let me try to break this down so you guys actually understand what's going on here. My laptop’s internal ribbon cable finally kicked the bucket. So, until I can track down a replacement, I've been slaving away using an HDMI cable to hook the thing up to my TV. Here’s the headache: I don't get any video signal until after macOS boots up. There is absolutely zero image before the OS loads, which means I can't see a damn thing to get into the BIOS. I'm asking because I desperately need to wipe the drive and start fresh—this system has been crawling for months now, and honestly, it's been about two years since I last did a clean install, so it's beyond overdue. If anyone out there knows a workaround or some trick to trigger the BIOS through an HDMI connection, please, for the love of god, help me out.

frozenwolf51 said:I know the title is pretty vague, so let me try to explain what's going on here. The internal ribbon cable on my laptop died, so until I can get a replacement, I've been using an HDMI cable to hook it up to my TV. The problem is, I only get a picture once macOS boots up. I can't see anything early enough to actually get into the BIOS. I'm asking because I really need to wipe the drive and format it—the system has been running incredibly slow lately since it's been about two years old now. If anyone knows a way to access the BIOS through an HDMI connection, please help me out.

It’s the exact same deal as using a VGA or DVI cable. It doesn't matter that you can't see the screen yet. Just mash that key to enter the setup (depending on your specific model) immediately after you hit the power button. You can hammer it repeatedly; it won't hurt anything.