May have fried my ECU!! Need advice

[electrician22]

Ok hang with my story for a minute here because this has been quite the SAGA. I bought a 2009 1.8 with 220,000 miles about a month ago. When I test drove it the AC was cold and there were no CELs. Everything was clean and I was getting good *vibes* from the sellers. As I was literally driving it home after paying for it, the CEL came on along with the Trac control lights. The codes read by oreilly were p0354, p0420, c1201. I immediately ordered 4 denso ignition coils and also ordered an XTOOL code reader. Code reader came in first so I decided to try the new toy out and was having trouble getting it to communicate properly with the car. The next time we started the car it seemed to have a whole new slew of problems. The Power Steering wasn't working, AC wasn't working and a new set of dash lights came on...BRAKE, ABS, and POWER STEERING. Also the whole instrument cluster would not work...speedometer, tach, engine temp etc. I limped the car to oreilly to check codes and battery-alternator. They both passed oreilly's test and he COULD NOT get his code tester to communicate with the car. I checked and found no blown fuses in either fuse block....I checked a couple of grounding points and they seemed fine. I've now ordered an ECU from Flagship one for $231. I cannot imagine a reputable $300 code reader could have caused any problems??? I'm really stressed about this car and I hope there's still hope for it. Anybody have any other advice to give me? Thanks in advance.