Your problem sounds suspiciously like a fault (corrosion) in the wiring loom beneath the radiator. This is a well known problem on these models and you will find multiple references to it on this forum.
While I cannot be certain that the wires to the lights and rear wiper actually are among the large number of wires running in the loom beneath the radiator the fact that the problem arose after having disturbed the wiring loom would strongly indicate this to be the problem. It is also supported by the fact that the fuses, bulbs etc appear OK.
I suffered this problem several years ago and wrote about it on this forum, I suggest you read this before buying any more replacement parts:
http://www.volvoforums.org.uk/showthread.php?t=180349