Need help with a used 2004 Cadillac CTS 3.6l ECU

[DOC]

What does the smog place says is the reason you failed?

They said the onboard smog test stuff hasn't passed the tests yet. The cat, evap, O2 and O2 heater tests had not run yet and they kicked it out without further tests. I think I can have one not run yet. But I had 3 not run. There might be more issues going on to get it back to stock.
The brake lights were out and it was a bad soldier joint and that fixed it when I re soldiered the joints in a computer. A common problem with GMs.

Did you just recently buy this car?

Yeah. A month ago. I got it from my neighbor that had to get rid of it. His wife told him its cursed and needs to get rid of it. They are moving too and have to unload some of their stuff.

Has your battery died recently or been disconnected for a long time? If that is the case you will need to drive the car some distance so all the emissions equipment has had a chance to cycle a couple times, then the scan tool will then be able to retrieve the data on the equipment.

It has sat for a year and the battery was changed before I got it. I recently put in a good battery that I know was new. Optima Redtop 1000 ca 800 cca.
I think that is what I needed. I hate throwing parts at stuff though without knowing that is what is wrong. But some of the gauges are not working and even though the emissions stuff still works. The evap test won't run, because it has to see the gas tank between 1/4 and 3/4 full and it doesn't show anything. The temp gauge doesn't show anything either. I think they are run by the ECU so its not sending any info to the gauges.
The emissions test looked for the internal smog test to run and the catalyst test, evap, O2 sensor and O2 heater test need to run and those take time. During the last month I have gotten all to pass except the EVAP test to run. I think I can run the emissions test with one not run yet. Now the temp tag is expired. I ordered another one over the phone and it was a 10 day tag. It started the day I ordered it and it showed up on day 8. SMH.
I think I need it reflashed with a stock program. I have seen mechanics updating the firmware like they were updating their phone or something.