Just my thought here.
Any electrical problem is difficult to pin point as we know and you would have cleaned and secured battery terminals I guess.
Your is an 05 and you say last year it was OK, it could be one of many things especially if it's ECU related as it operates on internally on low voltage so corrosion is a factor or faulty ignition switch.
So my line of thinking is connections, poor contacts, fracture wire at steering head stock, mostly as mentioned.
I would go through all the multi plug connections form and including Ign Switch, under the tank plugs and ECU + relays connections.
I went through mine last year and cleaned and re greased with dialectic grease as a maintenance procedure.. found a few corroded plug pins under the tank on my 05.
It's a bit time consuming and fingers get sore but it had to be done at that age for reliability.
Just mentioning because you seem to have tried the obvious.
Hope this helps..