Chime then just blank screen after attempted install. MBP2015

After attempting to install OCLP on my 2015 MBP it will no longer boot. I hear a chime, and then it is just a blank screen. No progress bar, no icon. Just blank screen. Holding down any of the keys for recovery, diagnostic, startup disk menus, reset NVRAM seem to have no effect. No target mode.

Occasionally, I can get a flashing white folder icon in the middle of the screen.

I've tried booting to external USB drives with MacOS on them, but no go.

I'm guessing that somehow the firmware got corrupted.

Any suggestions on how to get it out of this bricked state?

submitted by /u/shannah78
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