Hey Muffman, my 2010 F4 did the same thing, I was out of town and wifey inadvertently turned off the power to the trickle charger on the OEM Koyo battery.
When my new Shorai LFX showed-up, all I got was Fans and a "Can-Line Fault" warning on the Dash.
I was Shitting Bricks.
I removed the ECU, and then just re-installed it, and apparently, it reset?
Problem went away, and never happened again.
Check battery connection, remember the battery lies on it's side, with the (+, Red) towards the rear of the bike.
If you did that right from the start, then put a charger on the battery, and like the guys said, check the fuses on the bike both left and right side.
Thanks guys im pretty sure ive hooked the battery up the wrong way round! Didnt realise it lies on its side, should have taken more notice of it when i took it out, hope i havnt done any damage! Will swap it round when i get home.
Just got home put the battery on its side, hooked it up and bike started with. No probs at all! I feel like a goose for hooking it up backwards but am thankfull nothing was damaged and really appreciate the info all of you gave me! This is my first italian bike and im loving it!!