Chosen Solution
changed EFI chip on iMac, read another thread where it stated that if not installed correctly then machine won’t boot. I micro-soldered it myself and all the connections look good. Is there a way to measure it? continuity test? voltage test?
Burn another chip and try it. There’s no means to check other than checking continuity from the pin to a point in the trace (if you’ve got a short or cold joint.
