RECKG - replacing the BCCIII would be a good idea.
I've never seen Bay 1 PCM errors on an ELX and the BCCIII would be the only likely candidate in my opinion.
When replacing the BCCIII, you need to allow it to download its software (20-30 minutes). If you did not wait previously AND the BCCIII you tried had already started its download before you aborted, then the BCCIII you have will need to be re-flashed before it can be used again.
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Occam's Razor - All things being equal, the simplest solution is the right one.