Find the missing truth before adding more calibration.
A vehicle that does not start can have a calibration issue, but it can also have a trigger, wiring, phase, fuel-pressure, output-assignment or mechanical problem. The first task is separating those causes.
For inherited projects, old calibration files, datalogs and the last known-good combination are especially valuable because they show what changed before the failure appeared.
After the engine is synchronized and the critical inputs/outputs are proven, the first-start calibration can be stabilized and advanced toward a complete dyno tune.
Current, base and known-good ECU file review when available.
Crank/cam signal and synchronization diagnosis.
Commanded versus measured base ignition timing verification.
Injector/coil/output assignment and basic sensor plausibility checks.
Controlled first start with oil/fuel pressure, leak and temperature monitoring.