Mercedes Benz repair: non starting, a/c blower dead, mercedes benz 420sel, number search results

Question
Hi!
I have an '87 420 sel, and I need advice on two problems.  It started with the blower going out in my a/c.  
1)The fan works, as I have hotwired it to check.  So, I replaced the porcupine (blower regulator), still no good.  Checked lines to porky with a circuit tester..looks like no power somewhere before regulator.  No fuses out, so I thought I'd blindly check the 12v 20-30A silver things (6 of them) in the fuse box.  The 2 nearest the front of the car were very hot after running the car for a minute.  So, I switched the front one (hot) nearest the passenger side with a one I got from a junkyard..had same markings, looked a little older.  This led to prob #2:
2) Now car wont start, even after replacing the original silver thing in the fuse box. I have fire to the plugs, turns over fine and car will run for a second or two using quickstart ether, then die.  No fuel to injectors?  Did I blow some kind of fuel inj. controller or fuse while playing with the silver things?  And what are those anyway?  Relays?

I should have let my mechanic have a go (a little bit of knowledge is a dangerous thing), but it took him a solid month just to change the ignition switch tumbler, and he never could  figure the blower thing out.

Thank you for your help!

Answer
Remove relays from fuse panel one at a time; lightly clean contact legs with 600 grit sand paper, and reinstall.
Remove all fuses and throw away, lightly clean fuse terminal contact legs with 600 grit sand paper, and install "NEW" fuses.

Test both sides of fuse terminal with a "test light" after new fuses are installed.

Possible bad Overload Relay?

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1987 Mercedes Benz 420SEL
Part: Overload Relay
 Note:  
 Year: -1987
P2056-18124 Overload Relay IN STOCK $69.73  
  
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=merc...

The silver cube is a relay.

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1987 Mercedes Benz 420SEL
Part: Relay
 Note:  
<br>Window regulator : Seat adjuster : Steering column.     
 Chassis: A-461998-
P2020-12007 Relay IN STOCK $41.16  
  
http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=cata...