Make sure you’re using an Apple kb to try and access OF/other key combos. Some kbs may not trigger this correctly.

Try to erase nvram with cmd+alt+n+v. Afair keeping those keys pressed as you press and hold power button with 3rd hand can help too. Do this while it’s powered off initially.

[ Edited by jacadcaps 31.05.2021 - 00:43 ]