Lenovo Y570 Project Bios and Display

[dNAUREZ]

EDIT* UPDATE- I was able to recover finally by removing and reflashing the Efeon buos chip. Can anyone provide any insight on why removing the CMOS didn't reset? * Thanks!

Hello! New here and stumbling around hoping for a little assistance. Self induced dilemma = I decided to build a ridiculous game box using a lenovo Y570 model# CB01061723 which was headed for e-waste due to cracked screen etc. I pulled the mobo and had it connected via hdmi. Full disclosure.... This poor thing will never have a battery again and now has the full 16gb ram and I fully intend to use an external gpu. I came across a V2.06 unlocked bios and after many failed attempts due to efi boot partition size, got it flashed. All was well until I fiddled with display options and managed to black screen. I pulled the CMOS and spammed the power button and let sit for hours to no avail. Gave up on that, pulled the Efeon chip and flashed the original bios back (which I dumped from the start) using a t48 programmer. Still black screen 😑. Yes I've properly poo'd the bed. Yes, this is a stupid project. This thing is a dinosaur but had all the I/O that would be perfect for a retro box. Anyone have any suggestions? Thanks in advance.

[dNAUREZ]

I'm not sure if this is the correct area to post BTW.
Once I get everything set up with the gpu, I'm wondering which bios video options would be proper. To start with a benchmark, I was going to use a cheap mini pcie adapter and modest EVGA gpu (connected to a separate PSU) I understand that there will be a performance impact this way but I'm not expecting miracles. If anyone has any suggestions I'm all ears... Thanks again