just got a used cbr1100xx 2001 model couple of months back, its been packed for 5months, tried to start after all checks, but failed to start.the dash board lights up but the bike would not crank.need some help.a friend thinks its the brain box.

 

Check the 30 amp fuse under the seat

The "brain box" - or ECU would not stop it cranking - it just wouldn't run

 

Yeah definately check the fuses and make sure the run/stop switch is functioning and make sure the battery is fully charged. 'Bird's are known for stator's and r/r's that cause these kind of problems too. Hope you get her running, cheers.

 

Try the simple things first. Is it in neutral, and is the neutral light on? If there's no light, you can still start it if you hold in the clutch and the sidestand is not down. If there is a neutral light and no crank check the stop button on the right handlebar. If it's off, then next suspect is the starter relay. You can short it out to see if it will crank.
All this supposes that the battery is nice and fresh. If the voltage is low (under about 11.6v I can't remember) the bike will not start. If you're not sure try all this with a known good battery.
Hope this helps.