Rep Power: 0

I’m going to make a very long story short. Replaced timing belt and sensors all of that, car is in time, etc etc. After putting back together, no power to car at all. Battery is good, so I replaced the alternator. Still nothing. Checked all grounds, all connections to battery with multimeter, alternator and battery are good, grounds are all good, checked every single connection I can get to, everything good. Checked fuses in engine bay, checked fuses under steering wheel and all good. Nothing. Tried a new battery, nothing. No power at all. What could be causing this? I need help please, I am completely lost and on my last leg with this car

 
Rep Power: 222

What do you mean by no power? You turn the key and no dash lights, no nothing? You turn the key and it doesn't crank? It doesn't start?
Did you take the caps off the battery terminals? All connections clean, tight, and shiny? Including ground connections? Are the battery connections the crappy aftermarket ones? Did you use oem sensors?

 
Rep Power: 126

How tight were the alternator bolts? Based off your current diag, and knowing how common a failure this is, you might’ve cooked your ECU.