The only thing that I can think of is that it may have been a ground strap for the old ABS1 control module case.
Not having had my hands on an ABS1 bike I can't say for certain. I don't recall seeing anything like that on my later LT's.
Your main battery ground should connect at the starter base bolts, so make sure they are in place.
You said that the side stand switch was bypassed, make sure you didn't "undo" that bypass.
What happens when you turn on the key, dash lights, fuel, temp gauges move?