I just bought a 2004 S60 from a private party and 2 days after I got it my dashboard stopped working when I went to start the car.

When I start the car the dashboard lights up dimly. SRS warning light is on. Then as the guages are turning on it just shuts off.
Check engine light stays on all the time but the rest of the dash is dead after startup.
Power locks do not work.
Front windows work but rear do not.
Mirror adjusters do not work.
Sunroof does not work.
Turn signals do not work.
High beams do not work but headlights do.
Washer fluid does not spray. Wipers work, but always in high speed no matter the setting and they stop where they are if I turn them off so I have to time it to not have them still be up when I stop using them.
AC does not work but fan does. Climate control lighting works.
Radio works.
Shifter lighting does not work to see what gear I'm in.
Lastly, all of my acceleration is gone. Trying to get the car moving from a stop is like going up a steep hill in a weak car. It takes almost 20-30 seconds to get from 0-15 mph no matter how much gas I give it, but once I get moving it has no problem going and I've gotten over 60 mph like this so I don't think I'm limited anywhere but startup from a stop is atrocious.

I've been doing a lot of research and it seems like it is either the DIM itself or my CEM is failing. I am leaning toward the CEM because I heard they have a strong overheating problem in the 04' especially and it has been 90 degrees plus, really humid and rainy ever since I bought the car. I would however like to hear if anyone has had similar problems or thinks they know which part might be the problem because both are a little pricey to fix and I don't wanna pay for the wrong one and have to pay again. Thank you.