If you cannot get the codes then you have to determine what is missing or which system is malfunctioning. There may be some redundantcy here but you need to start at the beginning of no start diagnostics.
If you can retrieve codes it will make things easier.
When testing while cranking the engine unplug the fuel pump so you do not flood the engine again.Be sure the oil is not fuel diluted from the previous flooding problem, this will create a rich mixture and will wash down the cylinder walls while cranking/running.
You stated that rats chewed the interior wiring, Your Logic Module is located behind the R/S Kick panel, be sure that the wiring is still intact and not damaged and that the vacuum supply line to the MAP sensor(located on the LM) is not damaged.
To be sure start by checking all of the power supplies to the LM and LM grounds, without a scanner you will not know about sensor inputs or output commands to sensors/solenoids without checking each circuit manually.
If all is ok proceed.....
Start by testing the ASD relay circuit. The ASD powers the fuel pump, injectors and ignition coil. Leave the fuel pump connected for this test.
Locate the underhood diagnostic connector(in the harness near the controller) and with the key on/engine off ground the DB/YL wire, this will actuate the ASD, the fuel pump should run, and there should be power at the DG/BK wire at the injector harness and at the + coil.
If 1 or more is missing post back.
If all is present remove the ground wire, unplug the fuel pump and while cranking the engine for 10 seconds check for constant power at the + coil.
If it is present the HEP circuit is good, if no power post back.
Next connect a fuel pressure gauge and be sure static fuel pressure is good and holding, grounding the DB/YL wire as you did earlier will make the pump run and you can read static pressure(53-57 psi) and when you remove the ground and the pump stops the pressure should hold, if it drops suddenly post back.
If pressure is good and holding check for strong and consistant spark from the coil wire to ground(hold wire 1/4" from ground, any further could result in controller damage) and at the spark plugs.
If no spark is present post back, if spark is present the other items that will affect fuel are injector control circuits( a noid light will tell you if the injectors are being pulsed) MAP Sensor circuit, Coolant Temp sensor circuit.