PPPP just means there is no communication between cluster chip and the OBC. As you probably did remove the battery when you installed the starter: did you reset time and date on the OBC again? Try that.
Here is the onwers handbook where you can see how to do that and also the OBC training reference handbook
http://www.bimmernut.com/forum/showt...andbook-manual
In my opinion this however has no relation to the no start of the engine.
The OBC drive away protection is a very simple thing, it would call for a 4 digit code, but you get PPPP which means no data transfer.
Wiring diagrams are here by built year http://shark.armchair.mb.ca/~dave/BMW/e34/
AND, you have to find out why the fuse was burnt, that maybe has some relation to your problem. What fuse # was it? Why was it melted? What else is covered by that fuse? See above link to wiring diagrams, from around page 14 all items are listed by fuse #.
Did you check the fuses under rear seat already?
And the fusable links? http://www.bmwe34.net/E34main/Mainte...sible_link.htm