1999 Pontiac sunfire electrical problem.

I had corroded connections and frayed wires going to my ecu and I had that serviced and I went to go start my car and everything was normal then all of a sudden, no power at all. Turned key off, checked fuses, and all were good. I then turned my key again to try and see if it was just a fluke and my air bag light dimly came on in the acc position and nothing when turned to on. The air bag light was the only light that came on also. Any thoughts on what it might be? Oh and I just remembered that he had re-soldered the wires and replaced the 373 power wire. I don’t have a multimeter at the moment to check the battery but I am goin to get one tomorrow and let you all know what the voltage is and if I find anything else.