Goofed, dammit, and need diagnostic advice.

[Apeman]

First, to any of y'all who are married, you know how this can happen:

Installing the battery in my half-restored 96 Sportster.
I look at the recently charged battery, note the terminal polarities, pick it up and drop it in the battery holder in the boat.
As I'm about to attach the cables, the missus comes toward me, bellering about something I cannot comprehend, as I have my head in the enginewell. I pull my head out, ask what the crisis is. and proceed to yakk about stupid bs. Later, I dove back in and connected the terminals. I don't think I need to tell you all which way I connected the battery cables.
Big surprise, no power, no MPEM beeps. no start, no nothing but trouble. I look and see what I did, and proceed with the cussing for the next 10-15 minutes.
I'm really hoping there's a dumb-ass protection circuit and fuse that saved me here. If not, I probably cooked my MPEM, didn't I?
I wanted to spend time diagnosing, but the rest of the day was booked and I'm at work today. I plan to open up the box and check fuses tonight.
Any advice? (other than earplugs)
-az-

 

[snikwad003]

Cross your fingers and check all the fuses but you could be in for the worst. In certain circumstances you can dig the potting out and replace the burnt device on the board but I'm not real clear on that. If it is bad news you can tell the wife she just spent a ton of money on the boat with her mouth, that usually doesn't work for my plans tho

 

[Apeman]

Well, I had a chance to pull the mpem cover and check the fuses. The 5a that feeds the MPEM logic popped.
I sure hope it saved my arse.
I'll check tonight if it stops raining long enough to install a spare.
-az-

 

[illru]

Made my teeth hurt reading that. Hope luck is on your side!

 

[Apeman]

That 5a fuse was in that circuit for exactly what happened I think. I'll bet there's a clamping diode just past the fuse in the inside, that clamps to ground if it sees reverse voltage. The blown fuse appears to be the only damage. Got the very welcome 2 beeps as soon as I applied the key, and after a good choke session, she popped right off.
I am going to spray paint the entire top half of the battery red (on the positive side, hopefully) so there's no question about polarity when looking into a dark engine well.

Illru, I hope your teeth have recovered.
Thanks again guys, this place is a superb resource and the folks who hang out here are golden.

 

[snikwad003]

You got lucky as chit, $1500 for that old mpem, if you find one for sale.

 

[Apeman]

Lucky is right, that's what I paid for the boat, bimini top, and trailer.
Sheesh....