I am new to this group and I apologize if I ask something that has been answered before.
My 2001 C320, out of warranty now, needed a new battery and I thought I would save some $ and replace it myself (stupid me).
However, after replacing it, the following items are no longer operational:
1. Wipers
2. Hazards/ Turn Signals
3. Rear sunshade
4. Trunk won't open from inside switch
5. Key remotes won't unlock trunk
6. Key remotes won't unlock doors, unless key is 1 foot or less from door
handle (I checked the batteries and both remotes)
7. Alarm
8. Fuel gauge shows 0 fuel all the time
9. The message display on the dash says 'Faulty Display'.

The wipers were acting funny a day before, when I had them on intermittent.
I was also getting strange error codes on the day the battery was low.

I checked all the fuses and none are blown.

I scanned the boards and found that this is more likely because a few relays have failed. Please let me know if you think this is the case.

If it is, could someone offer some help on how to identify the defective relay?
I see those 'cubes' on the fuse boards, are those the relays? How can I find out which ones correspond to the functions I described above? Lastly, where can I buy relays? (fastlane has none for my car)

I may sound like a novice when asking these questions, but this is not the case. I have performed major mechanical repairs on my cars, just not electrical. Yet, I have fixed electrical components for TVs and applicances. Bottom line, feel free to give advise that is complex to follow. Its not that I can't do it, but I won't touch this car's electronics without getting some advise first.


Thank you in advance!