MS1 not reading tach input

[dochka]

Hi,
A friend of mine was tinkering with the wiring of his ms1 powered alfa-romeo car and caused a short;
There is connection between the laptop and ecu, all sensors read correct, but the cranking signal is lost
What components are possibly fried, what to look at next ?

Thank you

[slow_hemi6]

Vr or opto/hall input circuit? Which ever, that's probably where to start.