With the key on the theft light should not be flashing as long as there is no PATS issue.
With the key on the check engine light should be on if the PCM is powering up.
See if it will crank in neutral, if so then there is a transmission TR sensor or shifter linkage issue.
Remove the starter relay under the dash. Pin 30 should be power, pin 86 should be power when trying to start from the ignition switch and TR sensor, pin 85 should be ground from the PCM, monitoring the PATS system.
If you turn the key on, it should crank when briefly jumping pins 30 and 87 and possibly start.
Let me know these results.
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