"Thing is, I used an xl one, and not the dsi patch." - What?
Anyways if it's not even being recognized by a DS Lite, then it sounds like the update's corrupt. You may have accidentally hit the button a second time to start the update process right before cutting the system off (we've seen it happen).
Any way to fix it would require a second flash cart and the DS Lite. You'd start up the DSL version of the update file on the first cart, then take it out and pop in the bricked R4i Gold, then press A to do the check and apply the update, overwriting the broken parts of the R4i Gold's bootloader with a fixed copy.