HI Brooksy, welcome to the forum
Unfortunately electrical problems can be a real pain to nail, but the diagnostic codes in Gliders post will narrow it down, I had my red key light come on when riding, following the instructions that Glider has put up I was able to narrow it down to a faulty TSSM (
Turn
Signal
Security
Module) my dealer ordered me a new one under warranty as they did not have one in stock, long story short I convinced them to pull a TSSM from an 883 and swapped mine out, low and behold it wasn't the TSSM...:nosad
If I switched off the ignition and switched it on again it cleared the code and everything was fine again, the HD tech was left scratching his head as my turn signals would also pack up pointing to a faulty TSSM aswell.
We pulled the seat off and started to work our way along the bikes harness and didn't have to look too far as directly under the seat the left turn signal wire had been pinched between the bike frame and seat causing a short, we cut the damaged piece out crimped the wire back together and relocated it alongside the framework job done...

Untill you look to see if you have any trouble codes
09-08-07 DTC Codes - Harley Davidson Community this is realy like looking for the preverbeal needle in the haystack.
However dead batterys and 07/08 sportsters have had issues, read the below thread to see if this throws any light on your current problem.
XL883C Odd Noise - Harley Davidson Community
I know it's frustrating but you will be up and running again...:Banane09: