HP-67 - 1612A03018 - Card Reader Advice Requested (was HP-67 - strange behavior)

[albertofenini]

Thanks Tony,
that's a good hint, now tell me if'm wrong:
Can I say that from an electrical standpoint the PSU works fine ?
If PSU was not to be working I shouldn't be able to get the display lit up, right ?
Since the unit was working before we cleaned it with water and vinegar, can I say that
because of that degraded around the ROM chip ?
Which chip is ROM0 and what can we measure to check what's wrong ?
Would you suggest to remove it and re-solder it ?
Thanks for help Alberto